
Class 



Book. J l 7 
(topyiightN 



(COPYRIGHT DEPOSIT. 



(sHf 



American Mature Series; 

Group IV. Working with Nature 



INSECTS AND DISEASE 

A POPULAR ACCOUNT OF THE WAY IN WHICH 

INSECTS MAY SPREAD OR CAUSE SOME 

OF OUR COMMON DISEASES 



WITH MANY ORIGINAL ILLUSTRATIONS FROM 
PHOTOGRAPHS 



BY 

RENNIE W. DOANE, A.B. 

Assistant Professor of Entomology 
Leland Stanford Junior University 






NEW YORK 

HENRY HOLT AND COMPANY 
1910 



3> 



' 



Copyright, 1910, 

BY 

HENRY HOLT AND COMPANY 



Published August \ iqto 



THE QUINN A BODEN CO. PRESS 
RAHWAY, N. i. 



HI A2736 



PREFACE 

The subject of preventive medicine is one that is 
attracting world-wide attention to-day. We can hardly 
pick up a newspaper or magazine without seeing the 
subject discussed in some of its phases, and during the 
last few years several books have appeared devoted 
wholly or in part to the ways of preventing rather than 
curing many of our ills. 

Looking over the titles of these articles and books 
the reader will at once be impressed with the impor- 
tance that is being given to the subject of the relation 
of insects to some of our common diseases. As many 
of these maladies are caused by minute parasites or 
microbes the zoologists, biologists and physicians are 
studying with untiring zeal to learn what they can in 
regard to the development and habits of these organisms, 
and the entomologists are doing their part by studying 
in minute detail the structure and life-history of the 
insects that are concerned. Thus many important 
facts are being learned, many important observations 
made. The results of the best of these investigations 
are always published in technical magazines or papers 
that are usually accessible only to the specialist. 

This little book is an attempt to bring together and 
iii 



iv Preface 

place in untechnical form the most important of these 
facts gathered from sources many of which are at present 
inaccessible to the general reader, perhaps even to 
many physicians and entomologists. 

In order that the reader who is not a specialist in 
medicine or entomology may more readily understand 
the intimate biological relations of the animals and 
parasites to be discussed it seems desirable to call atten- 
tion first to their systematic relations and to review 
some of the important general facts in regard to their 
structure and life-history. This, it is believed, will 
make even the most complex special interrelations of 
some of these organisms readily understandable by all. 
Those who are already more or less familiar with these 
things may find the bibliography of use for more ex- 
tended reading. 

My thanks are due to Prof. V. L. Kellogg for reading 
the manuscript and offering helpful suggestions and 
criticisms. 

Unless otherwise credited the pictures are from 
photographs taken by the author in the laboratory and 
field. As many of these are pictures of live specimens 
it is believed that they will be of interest as showing 
the insects, not as we think they should be, but as they 
actually are. Mr. J. H. Paine has given me valuable 
aid in preparing these photographs. 

R. W. D. 
Stanford University, California, 

March, 1910. 



CONTENTS 



CHAPTER I 

PAGE 

Parasitism and Disease i 

Definition of a parasite, i; examples among various ani- 
mals, 2; Parasitism, 3; effect on the parasite, 4; how a harmless 
kind may become harmful, 5; immunity, 6; Diseases caused by 
parasites, 7; ancient and modern views, 7; Infectious and con- 
tagious diseases, 8; examples, 9; importance of distinguishing, 
9; Effect of the parasite on the host, 9; microbes everywhere, 10; 
importance of size, 11; numbers, 11; location, 11; mechanical 
injury, 12; morphological injury, 13; physiological effect, 13; 
the point of view, 14. 



CHAPTER II 

Bacteria and Protozoa 15 

Bacteria, 15; border line between plants and animals, 15; 
most bacteria not harmful, 15; a few cause disease, 15; how 
they multiply, 15; parasitic and nonparasitic kinds, 17; how a 
kind normally harmless may become harmful, 18; effect of the 
bacteria on the host, 18; methods of dissemination, 18. Pro- 
tozoa, 19; Amoeba, 19; its lack of special organs, 19; where 
it lives, 19; growth and reproduction, 19; Classes of Protozoa, 
20; the amoeba-like forms, 20; the flagellate forms, 20; im- 
portance of these, 21; the ciliated forms, 22; the Sporozoa or 
spore-forming kinds, 22; these most important, 23; abun- 
dance, 23; adaptability, 23; common characters, 24; ability to 
resist unfavorable conditions, 24. 

v 



vi Contents 

CHAPTER III 

PAGE 

Ticks and Mites 26 

Ticks, 26; general characters, 27; mouth-parts, 27; habits, 
27; life-history, 27; Ticks and disease, 28; Texas fever, 28; its 
occurrence in the north, 28; carried by a tick, 29; loss and 
methods of control, 31; other diseases of cattle carried by ticks, 
31; Rocky Mountain spotted fever, 32; its occurrence, 32; 
probably caused by parasites, 32; relation of ticks to this dis- 
ease, 33; Relapsing Fever, 33; its occurrence, 34; transmitted 
by ticks, 34; Mites, 35; Face-mites, 35; Itch-mites, 36; Harvest- 
mites, 37. 

CHAPTER IV 

How Insects Cause or Carry Disease 40 

Numbers, 40; importance, 41; losses caused by insects, 41; 
loss of life, 42; The flies, 43; horse-flies, 43; stable-flies, 44; 
surra, 45; nagana, 45; black-flies, 46; punkies, 46; screw-worm 
flies, 47; blow-flies, 48; flesh-flies, 48; fly larvae in intestinal 
canal, 49; bot-flies, 50; Fleets, 52; jigger-flea, 53; Bedbugs, 54; 
Lice, 54; How insects may carry disease, 55; in a mechanical 
way, 55; as one of the necessary hosts of the parasite, 56. 



CHAPTER V 

House-flies or Typhoid-flies 57 

The old attitude toward the house-fly, 57 ; its present stand- 
ing, 58; reasons for the change, 58; Structure, 59; head and 
mouth-parts, 60; thorax and wings, 61; feet, 62; How they 
carry bacteria, 62; Life-history, 63; eggs, 63; ordinarily laid in 
manure, 63; other places, 63; habits of the larvae, 64; habits of 
the adults, 64; places they visit, 65; Flies and typhoid, 65; 
patients carrying the germs before and after they have had the 
disease, 65; how the flies get these on their body and distribute 
them, 66; results of some observations and experiments, 66; 
Flies and other diseases, 68; flies and cholera, 68; flies and tu- 



Contents vii 



berculosis, 69; possibility of their carrying other diseases, 70; 
Fighting flies, 71; screens not sufficient, 71; the larger prob- 
lem, 71; the manure pile, 72; outdoor privies, 72; garbage can, 
72; cooperation necessary, 72; city ordinances, 73; an expert's 
opinion of the house-fly, 73; Other flies, 75; habits of several 
much the same but do not enter house as much, 75; the small 
house-fly, 75; stable-flies, 75; these may spread disease, 75. 

CHAPTER VI 

Mosquitoes 76 

Numbers, 76; interest and importance, 76; eggs, 77; always 
in water, 77; time of hatching, 77; Larva, 78; live only in wa- 
ter, 78; head and mouth -parts of larvae, 78; what they feed on, 
78; breathing apparatus, 79; growth of the larvae, 80; Vupce, 
80; active but takes no food, 80; breathing tubes, 80; how the 
adult issues, 81; The Adult, 81; male and female, 81; how mos- 
quitoes "sing" and how the song is heard, 82; the palpi, 82; 
The Mouth-parts, 2>y, needles for piercing, 8^; How the mos- 
quito bites, 84; secretion from the salivary gland, 84; why males 
cannot bite, 84; blood not necessary for either sex, 84; The 
Thorax, 85; the legs, 85; the wings, 85; the balancers, 85; the 
breathing pores, 86; The abdomen, 86; The digestive system, 
86; The salivary glands, 87; their importance, 87; effects of a 
mosquito bite, 87; probable function of the saliva, 88; How 
mosquitoes breathe, 89; Blood, 90; in body cavity, 90; heart, 90; 
Classification, 91; Anopheles, 91; distinguishing characters, 92; 
eggs, 92; where the larvae are found, 93; Yellow fever mosquito, 
94; its importance, 94; the adult, 95; habits, 95; habits of the 
larvae, 95; Other species, 96; some in fresh water, others in 
brackish water, 96; Natural enemies of mosquitoes, 97; how 
natural enemies of mosquitoes control their numbers, 98; mos- 
quitoes in Hawaii, 98; Enemies of the adults, 99; Enemies of 
the larvcB and pupae, 100; Fighting mosquitoes, 101; fighting 
the adult, 102; Fighting the larva, 103; domestic or local 
species, 104; draining and treating with oil, 104; combatting 
salt-marsh species by draining, 105; by minnows or oil, 105. 



viii Contents 

CHAPTER VII 

PAGE 

Mosquitoes and Malaria 106 

Early reference to malaria, 106; its general distribution, 106; 
theories in regard to its cause, 107; insects early suspected, 107; 
The parasite that causes malaria, 108; studies of the parasite, 
108; Life-history in human host, 109; its effect on the host, no; 
the search for the sexual generation, in; The parasite in the 
mosquito, 112; review of whole life-history, 115; malaria trans- 
mitted only by mosquitoes, 115; Summary, 117; experimental 
proof, 118. 

CHAPTER VIII 

Mosquitoes and Yellow Fever 120 

A disease of tropical or semi-tropical countries, 120; out- 
breaks in the United States, 120; parasite that causes the dis- 
ease not known, 121; formerly regarded as a contagious dis- 
ease, 122; The yellow fever commission, 123; Dr. Finlay's 
claim, 124; experiments made by the commission, 125; sum- 
mary of results, 129; what it means, 130; results in Havana, 
131; the fight in New Orleans, 132; In the Panama canal zone, 
135; in Rio de Janiero, 136; claims of the French commission, 
138; habits of stegomyia, 139; breeding habits, 139; possible 
results of war against the mosquitoes, 139; Danger of this dis- 
ease in the Pacific Islands, 140. 

CHAPTER IX 

Fleas and Plague 142 

Great scourges, 142; the "black death," 142; old conditions 
and new, 143; How plague was controlled in San Francisco, 
143; Indian Plague commission, 144; Dr. Simond's claim, 
145; The advisory committee and the new commission, 146; 
Results of Dr. Virjbitski's experiments, 147 ; Results of various 
investigations, 150; structure and habits of fleas, 151; feeding 
habits, 152; Common species of fleas, 153; Ground squirrels and 
plague, 155; squirrel fleas, 156; Remedies for fleas, 157; cats 
and dogs, 159. 



Contents ix 

CHAPTER X 

PAGE 

Other Diseases, Mostly Tropical, Known or Thought to 

Be Transmitted by Insects 161 

Sleeping Sickness, 161; its occurrence in Africa, 161; caused 
by a Protozoan parasite, 162; the tsetse-fly, 163; Elephan- 
tiasis, 164; caused by parasitic worms, 169; their development, 
165; how they are transferred to man, 165; effect on the pa- 
tient, 166; Dengue, 168; other names, 168; probably trans- 
mitted by mosquitoes, 170; Mediterranean fever, 171; cause, 
171; may be conveyed by mosquitoes, 171; Leprosy, 171; 
caused by a bacteria parasite, 171; possibilities of flies, mos- 
quitoes and other insects transmitting the disease, 172; Kala- 
azar, 173; transmitted by the bedbug, 173; Oriental sore, 174; 
the parasite may be carried by insects, 174. 

Bibliography . . 175 

Parasites and parasitism, 175; Protozoa, 176; Bacteria, 177; 
Insects and disease, 178; Mosquitoes — systematic and general, 
179; Mosquito anatomy, 182; Mosquitoes — life-history and 
habits, 183; Mosquito fighting, 183; Mosquitoes and disease, 
185; Malaria, 186; Yellow fever, 189; Dengue, 192; Filarial 
diseases and elephantiasis, 193; Leprosy, 193; Plague, 194; 
Fleas, 198; Typhoid fever, 199; House-flies — anatomy, life- 
history, habits, 200; House-flies and typhoid, 202; House-fly 
and various diseases, 203; Human myiasis, 207; Stomoxys 
and other flies, 208; tsetse-flies, 209; Typanosomes and Try- 
panosomiasis, 210; Sleeping sickness, 211; Rocky mountain 
fever and ticks, 212; Ticks and various diseases, 213; Kala- 
azar and bedbugs, 216; Text or reference books, 216; Miscel- 
laneous articles, 218. 



ILLUSTRATIONS 



An artificial lake, nearly dry and partly 
ftlled with rubbish, has become a breeding- 
GROUND FOR DANGEROUS MOSQUITOES . . Frontispiece 

PAGE 

Fig. i. A lamprey 2 - 

Fig. 2. Sacculina 2 

Fig. 3. Trichina spiralis 2 

Fig. 4. An external parasite, a bird-louse (Lipeurus 

ferox) 3 

Fig. 5. An internal parasite, a tachina fly {Blephari- 

peza adusta) 3 

Fig. 6. Work of an internal parasite, puss-moth larva 

parasitized by a small ichneumon fly ... 3 

Fig. 7. Typhoid fever bacilli 20 * 

Fig. 8. Amceba 20 

Fig. 9. Euglina virdis 21 

Fig. 10. Spirocheta duttoni 21 

Fig. 11. Paramecium 22. 

Fig. 12. Vorticella 22 

Fig. 13. Pathogenic protozoa; a group of intestinal 

parasites 22 

Fig. 14. Castor-bean tick {Ixodes ricinus) 28 

Fig. 15. Texas fever tick 28 

Fig. 16. Texas fever tick {Mar gar opus annulatus) . . T 29 

Fig. 17. Amblyomma variegatum 29 

Fig. 18. Ornithodoros moubata 36 

Fig. 19. The follicle mite {Demodex folliculorum) ... 36 

Fig. 20. Itch-mite {Sar copies scabiei) 37 

Fig. 21. Harvest-mites or "jiggers" 37 

Fig. 22. Horse-fly {Tabanus punctifer) 44 ' 

xi 



xii Illustrations 



PAGE 



Fig. 23. Stable-fly (Stomoxys calcitrans) 44 

Fig. 24. A black-fly {Simulium sp.) 45 

Fig. 25. Screw- worm fly {Chrysomyia macellaria) ... 45 

Fig. 26. Blow-fly (Calliphora vomitoria) 45 

Fig. 27. Bluebottle fly {Lucilia sericata) 50 

Fig. 28. Flesh-fly (Sarcophaga sp.) 50 

Fig. 29. "The little house-fly" {Homalomyia canicu- 

laris) 51 

Fig. 30. Horse bot-fly (Gastrophilus equi.) 51 

Fig. 31. Ox- warble fly (Hypoderma lineata) 51 

Fig. 32. Sheep bot-fly {Gastrophilus nasalis) 51 

Fig. S3- Chigo or jigger-flea, male (Dermatophilus pene- 
trans) 54 

Fig. 34. Chigo, female distended with eggs 54 

Fig. 35. Bedbug {Cimex lectularis) 55 

Fig. 36. Body-louse {Pediculus vestimenti) 55 

Fig. 37. One use for the house-fly 57 

Fig. 38. The house-fly {Musca domestica) 58 

Fig. 39. Head of house-fly showing eyes, antenna and 

mouth-parts 60 

Fig. 40. Proboscis of house-fly, side view 60 

Fig. 41. Lobes at end of proboscis of house-fly showing 

corrugated ridges 6l 

Fig. 42. Wing of house-fly 61 

Fig. 43. Wing of stable -fly {Stomoxys calcitrans) .... 62 
Fig. 44. Wing of house-fly showing particles of dirt 

adhering to it 62 

Fig. 45. Last three segments of leg of house-fly ... 62 

Fig. 46. Foot of house-flv 63 

Fig. 47. Larva of house-fly 63 

Fig. 48. Barnyard filled with manure 64 

Fig. 49. Dirty stalls 65 

Fig. 50. Pupa of house-fly 76 

Fig. 51. Head of stable-fly 76 

Fig. 52. Mass of mosquito eggs {Theobaldia incidens) . . 76 

Fig. 53. Mosquito eggs and larvae {T. incidens) .... 77 

Fig. 54. Mosquito larva {T. incidens), dorsal view ... 77 



Illustrations xiii 

PAGE 

Fig. 55. Eggs, larv^: and pup,e of mosquitoes (T. inci- 

dens) 78 

Fig. 56. Larva of mosquito (T. incidens) 78 

Fig. 57. Mosquito larvae and pup,e {T. incidens) .... 79 

Fig. 58. Anopheles larvae (A. maculipennis) 79 

Fig. 59. Mosquito pup.e (J. incidens) 80 

Fig. 60. Mosquito pupa (T. incidens) 80 

Fig. 61. Mosquito larvae and pup,e {T. incidens) .... 80 

Fig. 62. A female mosquito (T. incidens) 81 

Fig. 63. A male mosquito {T. incidens) 81 

Fig. 64. Head and thorax of female mosquito (Ochlero- 

tatus lativittatus) 82 

Fig. 65. Head and thorax of male mosquito (0. lativitta- 
tus) 82 

Fig. 66. Head of female mosquito 83 

Fig. 67. Cross-section of proboscis of female and male 

mosquito 83 

Fig. 68. Wing of mosquito (0. lativittatus) 86 

Fig. 69. End of mosquito wing highly magnified ... 86 
Fig. 70. Diagram to show the alimentary canal and 

salivary glands of a mosquito 87 

Fig. 71. Salivary glands of mosquitoes 87 

Fig. 72. Heads of culicln,e mosquitoes 90 

Fig. 73. Heads of anophelin^e mosquitoes 90 

Fig. 74. Wing of Anopheles maculipennis 90 

Fig. 75. Wing of Theobaldia incidens 90 

Fig. 76. A non-malarial mosquito (T. incidens), male, 

standing on the wall 91 

Fig. 77. Female of same 91 

Fig. 78. A malarial mosquito (A. maculipennis), male, 

standing on the wall 91 

Fig. 79. Female of same 91 

Fig. 80. Egg of Anopheles, side view 92 

Fig. 81. Egg of anopheles, dorsal view 92 

Fig. 82. Anopheles larvae 92 

Fig. 83. Anopheles larv^: 93 

Fig. 84. Anopheles larva, dorsal view 93 



xiv Illustrations 

PAGE 

Fig. 85. Anopheles pup,e resting at surface of water . 93 
Fig. 86. Salt-marsh mosquito (Ochlerotatus lativittatus); 

MALE 98 

Fig. 87. Salt-marsh mosquito (O. lativittatus); female . . 98 

Fig. 88. Top-minnow (Mollienisia latipinna) 99 

Fig. 89. Dragon-flies 99 

Fig. 90. The young (nymph) of a dragon-fly 100 

Fig. 91. The cast skin {exuvce) of a dragon-fly nymph . 100 

Fig. 92. Diving-beetles and back-swimmers 101 

Fig. 93. Killifish (Fundulus heteroliatus) 102 

Fig. 94. Stickleback (Apeltes quadracus) 102 

Fig. 95. An old watering-trough, an excellent breeding- 
place FOR MOSQUITOES 103 

Fig. 96. Horse and cattle tracks in mud filled with 

WATER 108 

Fig. 97. A malarial mosquito {Anopheles maculipennis) 

MALE I08 

Fig. 98. A malarial mosquito (A. maculipennis) female . 109 
Fig. 99. Diagram to illustrate the life-history of the 

malarial parasite iio 

Fig. 100. Malarial mosquito (A. maculipennis) on the wall hi 
Fig. ioi. Malarial mosquito (A. maculipennis) standing on 

A TABLE Ill 

Fig. 102. Salt-marsh mosquito (O. lativittatus) standing on 

A TABLE Il8 

Fig. 103. Anopheles hanging from the ceiling .... 118 

Fig. 104. Yellow fever mosquito (Stegomyia calopus) . . 122 

Fig. 105. Rat-flea (Loemopsylla cheopis) ; male 152 

Fig. 106. Rat-flea (L. cheopis) ; female 152 

Fig. 107. Head of rat-flea showing mouth-parts . . . 153 

Fig. 108. Human-flea (Pulex irritans) ; male 153 

Fig. 109. Human-flea (P. irritans) ; female 156 

Fig. ho. Mouse-flea (Ctenopsyllus musculi); female . . . 156 

Fig. hi. Trypanosoma gambiense 164 

Fig. 112. Tsetse-fly 164 




INSECTS AND DISEASE 

CHAPTER I 
PARASITISM AND DISEASE 

PARASITES 

HE dictionary says that a parasite is a 
living organism, either animal or plant, 
that lives in or on some other organism 
from which it derives its nourishment 
for a whole or part of its existence. This defini- 
tion will serve as well as any, as it seems to include 
all the forms that might be classed as parasites. 
As a general thing, however, we are accustomed 
to think of a parasite as working more or less in- 
jury to its host, or perhaps we had better say 
that if it does not cause any irritation or ill ef- 
fects its presence is not noted and we do not think 
of it at all. 

As a matter of fact the number of parasitic 
organisms that are actually detrimental to the wel- 
fare of their hosts is comparatively small while the 
number of forms both large and small that lead 



2 Insects and Disease 

parasitic lives in or on various hosts, usually doing 
no appreciable harm, often perhaps without the 
host being aware of their presence, is very great in- 
deed. 

Few of the higher animals live parasitic lives. 
The nearest approach to a true parasite among 
the vertebrates is the lamprey-eel (Fig. i) which 
attaches itself to the body of a fish and sucks 
the blood or eats the flesh. Among the Crus- 
taceans, the group that includes the lobsters and 
crabs, we find many examples of parasites, the 
most extraordinary of which is the curious crab 
known as Sacculina (Fig. 2). In its early stages 
this creature is free-swimming and looks not 
unlike other young crabs. But it soon attaches 
itself to another crab and begins to live at the ex- 
pense of its host. Then it commences to undergo 
remarkable changes and finally becomes a mere 
sac-like organ with a number of long slender root- 
like processes penetrating and taking nourishment 
from the body of the unfortunate crab-host. 

The worms furnish many well-known examples 
of parasites, whole groups of them being especially 
adapted to parasitic life. The tapeworms, com- 
mon in many animals and often occurring in man, 
the roundworms of which the trichina (Fig. 3) that 
causes " measly" pork is a representative, are 




Fig. i 



/! W 




Fig. 2 



Fig. 3 



Fig. i — A lamprey. (After Goode.) 

Fig. 2 — Sacculina; A, parasite attached to a crab; B, the active larval con- 
dition; C, the adult removed from its host. (After Haeckel.) 

Fig. 3 — Trichina spiralis encysted in muscle of a pig. (From Kellogg's 
Elementary Zool.) 



V 




/ 




Fig. 5 



Fig. 4 




Fig. 6 



Fig. 4 — An external parasite, a bird-louse (Lipeurus ferox). 

Y\G. 5 — A tachina fly {Blepharipeza adusta) the larva of which 
is an internal parasite. 

FlG. 6— Work of an internal parasite, puss-moth larva parasi- 
tized by a small ichneumon fly. 



Parasitism and Disease 3 

familiar examples. These and a host of others 
al" show a very high degree of specialization fit- 
ting them for their peculiar lives in their hosts. 

From among the insects may be selected interest- 
ing examples of almost all kinds and degrees of 
parasitism, temporary, permanent, external, in- 
ternal (Figs. 4, 5, 6). Among them is found, too, 
that curious condition known as hyperparasitism 
where one animal, itself a parasite, is preyed upon 
by a still smaller parasite. 

"The larger fleas have smaller fleas 
Upon their backs to bite um, 
These little fleas still smaller fleas 
And so ad infinitum." 

Coming now to the minute, microscopic, one- 
celled animals, the Protozoa, we find entire 
groups of them that are living parasitic lives, de- 
pending wholly on one or more hosts for their ex- 
istence. Many of these have a very remarkable 
life-history, living part of the time in one host, 
part in another. The malarial parasite and others 
that cause some of the diseases of man and do- 
mestic animals are among the most important of 
these. 

PARASITISM 

Among all these parasites, from the highest to 
the lowest the process that has fitted them for a 



4 Insects and Disease 

parasitic life has been one of degeneration. While 
they may be specialized to an extreme degree in 
one direction they are usually found to have some 
of the parts or organs, which in closely related 
forms are well developed, atrophied or entirely 
wanting. As a rule this is a distinct advantage 
rather than a disadvantage to the parasite, for 
those parts or organs that are lost would be use- 
less or even in the way in its special mode of life. 

Then, too, the parasite often gives up all its inde- 
pendence and becomes wholly dependent on its 
host or hosts not only for its food but for its dissem- 
ination from one animal to another, in order that 
the species may not perish with the host. But in 
return for all this it has gained a life of ease, free 
from most of the dangers that beset the more inde- 
pendent animals, and is thus able to devote its 
whole time and energy to development and the 
propagation of the species. 

We are accustomed to group the parasites that 
we know into two classes, as harmful or injurious 
and as harmless, the latter including all those 
kinds that do not ordinarily affect our well-being in 
any way. But such a classification is not always 
satisfactory or safe, for certain organisms that to- 
day or under present conditions are not harmful 
may, on account of a great increase in numbers or 






Parasitism and Disease 5 

change of conditions, become of prime importance 
to-morrow. An animal that is well and strong may 
harbor large numbers of parasites which are living 
at the expense of some of the host's food or energy 
or comfort, yet the loss is so small that it is not 
noticed and the intruders, if they are thought of at 
all, are classed as harmless. Or we may at times 
even look upon them as beneficial in one way or 
another. "A reasonable amount of fleas is good 
for a dog. They keep him from brooding on being 
a dog." 

But should these parasites for some reason or 
other increase rapidly they might work great harm 
to the host. Even David Harum would limit the 
number of fleas on a dog. Or the animal might 
become weakened from some cause so that the 
drain on its resources made by the parasites, even 
though they did not increase in numbers, would 
materially affect it. 

Perhaps the most serious way in which para- 
sites that are usually harmless may become of 
great importance is illustrated by their introduc- 
tion into new regions or, as is more often the case, 
by the introduction of new hosts into the region 
where the parasites are found. Under normal con- 
ditions the animals of a given region are usually 
immune to the parasites of the same region. That 



6 Insects and Disease 

is, they actually repel them and do not suffer 
them to exist in or on their bodies, or they are 
tolerant toward them. In the latter case the 
parasites live at the expense of the host, but the host 
has become used to their being there, adapted to 
them, and the injury that they do, if any, is neg- 
ligible. 

But when a new animal comes into the region 
from some other locality the parasites may be ex- 
tremely dangerous to it. There are many strik- 
ing examples of this. Most of the people living 
in what is known as the yellow fever belt are im- 
mune to the fever. They will not develop it even 
under conditions that would surely mean infection 
for a person from outside this zone. Certain of 
our common diseases which we regard as of little 
consequence become very serious matters when in- 
troduced among a people that has never known 
them before. The cattle of the southern states 
are immune to the Texas fever, but let northern 
cattle be sent south or let the ticks which transmit 
the disease be taken north where they can get on 
cattle there, and the results are disastrous. 

Another striking example and one that is at- 
tracting world-wide attention just now is the 
trypanosome that is causing such devastation 
among the inhabitants of central Africa. With the 



Parasitism and Disease 7 

advent of white men into this region and the conse- 
quent migration of the natives along the trade 
routes this parasite, which is the cause of sleeping 
sickness, is being introduced into new regions and 
thousands upon thousands of people are dying as a 
result of its ravages. 

DISEASES CAUSED BY PARASITES 

Some two hundred years ago, after it became 
known that minute animal parasites were associ- 
ated with certain diseases and were the cause of 
them, it rapidly came to be believed that all our ills 
were in some way caused by such parasites, known 
or unknown. Further study and investigation 
failed to reveal the intruders in many instances 
and so it began to be doubted whether after all 
they were responsible for much that had been laid 
at their doors. Then after it was discovered that 
minute plant parasites, bacteria, were responsible 
for many diseases they in turn began to be accused 
of being the cause of most of the ills that the flesh 
is heir to. 

In later years we have come to adopt what seems 
to be a more reasonable view, for we can see and 
definitely prove that neither of these extreme views 
was correct but that there was much truth in each 
of them. To-day we recognize that certain diseases, 



8 Insects and Disease 

such as typhoid, cholera, tuberculosis and many 
others, are caused by the presence of bacteria in the 
body, and it is just as definitely known that such 
maladies as malaria and sleeping sickness are 
caused by animal parasites. 

Then there is a long list of other epidemic 
diseases, such as smallpox, measles and scarlet 
fever, the exact cause of which has not been de- 
termined. Many of these are believed to be due 
to micro-organisms of some kind, and if so they 
will almost certainly sooner or later be found. 
Curiously enough most of the diseases in this last 
class and many of those in the first are contagious, 
while all that are caused by animal parasites are, 
as far as is known, infectious but not contagious. 

INFECTIOUS AND CONTAGIOUS DISEASES 

It is important that we keep in mind this distinc- 
tion. By contagious diseases are meant those that 
are transmitted by contact with the diseased per- 
son either directly, by touch, or indirectly by the 
use of the same articles, by the breath or effluvial 
emanations from the body or other sources. Small- 
pox, measles, influenza, etc., are examples of this 
group. By infectious diseases are meant those 
which are disseminated indirectly, that is, in a 
roundabout way by means of water or food or 



Parasitism and Disease 9 

other substances taken into or introduced into the 
body in some way. Typhoid, malaria, and yellow 
fever, cholera and others are examples of this class. 
Thus it is evident that all of the contagious dis- 
eases may be infectious, but many of the infectious 
diseases are not as a rule contagious, although some 
of them may become so under favorable con- 
ditions. 

Just one example will show the importance of 
knowing whether a disease is contagious or in- 
fectious. Until a few years ago it was believed 
that yellow fever was highly contagious and every 
precaution was taken to keep the disease from 
spreading by keeping the infected region in strict 
quarantine. This often meant much hardship and 
suffering and always a great financial loss. We 
now know that it is infectious only and not con- 
tagious, and that all this quarantine was unneces- 
sary. The whole fight in controlling an outbreak 
of yellow fever or in preventing such an outbreak 
is now directed against the mosquito, the sole 
agent by which the disease can be transmitted 
from one person to another. 

EFFECT OF THE PARASITE ON THE HOST 

We have seen how a few parasites in or on an 
animal do not as a rule produce any appreciable 



io Insects and Disease 

ill effects. This is of course a most fortunate 
thing for us, for the parasitic germs are everywhere. 
There is perhaps "more truth than poetry" in 
the following newspaper jingle: 

"Sing a song of microbes, 

Dainty little things, 
Eyes and ears and horns and tails, 

Claws and fangs and stings. 
Microbes in the carpet, 

Microbes in the wall, 
Microbes in the vestibule, 

Microbes in the hall. 
Microbes on my money, 

Microbes in my hair, 
Microbes on my meat and bread, 

Microbes everywhere. 
Microbes in the butter, 

Microbes in the cheese, 
Microbes on the knives and forks, 

Microbes in the breeze. 
Friends are little microbes, 

Enemies are big, 
Life among the microbes is — 

Nothing 'infra dig.' 
Fussy little microbes, 

Millions at a birth, 
Make our flesh and blood and bones, 

Keep us on the earth." 

While of course most of these microbes are to be 
regarded as absolutely harmless and some as very 
useful, many have the power to do much injury if 



Parasitism and Disease 1 1 

the proper conditions for their rapid develop- 
ment should at any time exist. While the size of 
the parasite is always a factor in the damage that 
it may do to the host the factor of numbers is 
perhaps of still greater importance because of the 
power of very rapid multiplication possessed by so 
many of the smaller forms. 

Certain minute parasites in the blood may cause 
little or no inconvenience, but should they begin 
to multiply too rapidly some of the capillaries may 
be filled up and trouble thus result. Or take some 
of the larger forms. A few intestinal worms may 
cause no appreciable effect on the host, but as soon 
as their numbers increase serious conditions may 
come about simply by the presence of the great 
masses in the host even if they were not robbing it 
of its nourishment. Many instances are known 
where such worms have formed masses that com- 
pletely clogged up the alimentary canal. Such in- 
juries as these may be regarded as mechanical in- 
juries. Some parasites injure the host only when 
they are laying their eggs or reproducing the young. 
These may clog up passages or some of them may 
be carried to some more sensitive part of the body 
where the damage is done. The guinea- worm of 
southwestern Asia and of Africa lives in the body 
of its host for nearly a year sometimes attaining 



12 Insects and Disease 

a great length and migrating through the connect- 
ive tissue to different parts of the body causing no 
particular inconvenience until it is ready to lay its 
eggs when it comes to the surface and then great 
suffering may result. The African eye-worm is an- 
other example of a parasite causing mechanical 
injury only at certain times. It works in the 
tissues of the body sometimes for a long while, 
doing no harm unless it finds its way to the connect- 
ive tissue of the eyeball. 

It is known that many of the germs which cause 
diseases cannot get into the body unless the pro- 
tecting membranes have first been injured in some 
way. Thus the germs that cause plague and lock- 
jaw find their way into the system principally 
through abrasions of the skin. Many physicians 
have come to believe that the typhoid fever germ 
cannot get into the body from the intestine where it 
is taken with our food or drink unless the walls of 
the intestine have been injured in some way. It is 
well known that of the many parasites that inhabit 
the alimentary canal some rasp the surface and 
others bore through into the body cavity. This in 
itself may not be a serious thing, but if the mechani- 
cal injury thus caused opens the way for malignant 
germs, baneful results may follow. Even that 
popular disease appendicitis is believed to be due 



Parasitism and Disease 13 

sometimes to the injury caused by the work of 
parasites in the appendix. 

Parasites may cause morphological or struc- 
tural changes in the tissues of their hosts. The 
stimulation caused by their presence may result 
in swellings or excresences or other abnormal 
growths. Interesting examples of this are to be 
found in the way in which pearls are formed in 
various mollusks. In the pearl oysters of Ceylon 
occur some of the best pearls. If these are care- 
fully sectioned there may usually be found at the 
center the remains of certain cestode larvae whose 
presence in the oyster caused it to deposit the 
nacreous layers that make up the pearl. Other 
parasites cause similar growths in various shell- 
fish. The great enlargements of the arms or legs 
or other parts of the body seen in patients affected 
with elephantiasis is an abnormal growth due to 
the presence of the parasitic filarae in some of the 
lymph-glands where they have come to rest. 

Finally, the parasite may exert a direct physio- 
logical effect on the host. This is evident when the 
parasite demands and takes a portion of the 
nourishment that would otherwise go to the build- 
ing up of the host. Sometimes this is of little im- 
portance, but at other times it may be a matter of 
life or death to the infected animal. The physio- 



14 Insects and Disease 

logical effect produced may be due to the toxins or 
poisonous matters that are given off by the parasite 
while it is living in the host's body. Thus it is be- 
lieved that the malarial patients usually suffer less 
from the actual loss of red blood-corpuscles that 
are destroyed by the parasite than they do from 
the effects of the poisonous excretions that are 
poured into the circulation when the thousands 
of corpuscles break to release the parasites. 

One other point in regard to the relation of the 
parasite to its host and this part of the subject may 
be dismissed. From our standpoint we look upon 
the presence of parasites in the body as an ab- 
normal condition. From a biological standpoint 
their presence there is perfectly normal; it is a 
necessary part of their life. We think that they 
have no business there, but from the viewpoint of 
the parasites their whole business is to be just 
there. If they are not, they perish. And when we 
take a dose of quinine or other drug we are killing 
or driving from their homes millions of these little 
creatures who have taken up their abode with us 
for the time being. But they interfere with our 
health and comfort, so they must go. 




CHAPTER II 
BACTERIA AND PROTOZOA 

BACTERIA 

N the border line between the plant and 
the animal worlds are many forms which 
possess some of the characteristics of 
both. Indeed when an attempt is made 
to separate all known organisms into two groups 
one is immediately confronted with difficulties. In 
looking over the text-books of Botany we will find 
that certain low forms are discussed there as belong- 
ing with the plants, and on turning to the manuals 
of Zoology we will find that the same organisms are 
placed among the lowest forms of animals. The 
question is of course of little actual importance 
from certain points of view. It serves, however, to 
show the close relation of all forms of life, and from 
a medical standpoint it may be of very great im- 
portance owing to the difference in the life-habits, 
methods of reproduction and methods of trans- 
mission of many of the forms that cause disease. 
We have already seen that none of the diseases that 

is 



16 Insects and Disease 

are caused by animal parasites is contagious, while 
many of those caused by bacteria are both con- 
tagious and infectious. 

Just over on the plant side of this indefinite 
border line are the minute organisms known as 
bacteria. Their numbers are infinite and they are 
found everywhere. The majority of them are 
beneficial to mankind in one way or another, but 
some of them cause certain of the diseases that we 
will have to discuss later so attention may be called 
here to a few of the important facts in regard to 
their organization and life-history in order that we 
may better understand how they may be so easily 
transferred from one host to another. 

Although these bacilli are so extremely minute 
(Fig. 7), some of them so small that they cannot be 
seen with the most powerful microscopes, they 
differ in size, shape, methods of division and spore- 
formation. Each species makes a characteristic 
growth on gelatin, agar or other media upon which 
it may be cultivated. In this way as well as by the 
inoculation of animals the presence of the ultra- 
microscopic kinds may be demonstrated. 

The method of reproduction is very simple. 
They increase to a certain point in size, then divide. 
This growth and division takes place very rapidly. 
Twenty to thirty minutes is sufficient time in some 



Bacteria and Protozoa 17 

cases for a just-divided cell to attain full size and 
divide again. Thus in a few days time the number 
of bacteria resulting from a single individual would 
be inconceivable if they should all develop. 

Fortunately for us, however, they do not all 
multiply so rapidly as this and besides there are 
natural checks, not the least of which are the sub- 
stances given off by the bacteria themselves in 
their growth and development. Such excretions 
often serve to inhibit further multiplication. Some- 
times, though not often, they form spores which 
not only provide for a more rapid multiplication, 
but enable the organism to live under conditions 
that would otherwise prove fatal to it. 

Bacteria may be conveniently grouped under 
two heads : those that live upon dead organic mat- 
ter, known as the saprophytic forms, and those 
that are found in living plants or animals, the true 
parasites. Such a grouping is not always entirely 
satisfactory, for many of the kinds that live sapro- 
phytically under normal conditions may become 
parasitic if opportunity offers, and also many of 
those that are usually regarded as parasitic may be 
grown in cultures of agar or other media, under 
which conditions they may be regarded as living 
saprophytically. 

It is this power of easily adapting themselves 



1 8 Insects and Disease 

to different conditions that makes many of the 
kinds dangerous. The bacillus which causes 
tetanus or lockjaw will illustrate this. It is a 
rather common bacillus in soil in many localities. 
As long as it remains there it is of no special im- 
portance, but if it is introduced into the body 
through a scratch or any other wound it becomes 
a very serious matter. 

We may say, then, that the effect the bacillus has 
on the host depends largely on the host. Not only 
does it depend on what the host is, but the particu- 
lar condition of the host at the time of infection 
is of importance. Children are subject to many 
diseases that adults seldom have. Hunger, thirst, 
fatigue, exposure and other factors may make a 
person susceptible to the actions of certain bac- 
teria that would be harmless under other condi- 
tions. 

The minute size and great numbers of the bac- 
teria make their dissemination a comparatively 
simple matter. They may be carried in the air 
as minute particles of dust; they may be carried 
in water or milk; they may be carried on the cloth- 
ing or on the person from one host to another, or 
they may be disseminated in scores of other ways. 
In other chapters, particularly the one dealing with 
the house-fly and typhoid, we shall see how it is 



Bacteria and Protozoa 19 

that insects are often important factors in spread- 
ing some of the most dreaded of the bacterial dis- 
eases. 

THE PROTOZOA 

The Protozoa, or one-celled animals, belonged to 
an unknown world before the invention of the 
microscope. The first of these instruments enabled 
the early observers to see some of the larger and 
more conspicuous members of the group and each 
improvement of the microscope has enabled us to 
see more and more of them and to study in detail 
not only the structure but to follow the life-history 
of many of them. 

The Amoeba. With some, as the common amoeba 
(Fig. 8), a minute little form that is to be found in 
the slime at the bottom of almost any body of 
water, the life-history is extremely simple. The 
organism itself consists of a minute particle of 
protoplasm, a single cell with no definite shape or 
body-wall and no specialized organs or apparatus 
for carrying on the life-functions. It lives in the 
slime or ooze in fresh or salt water, takes its food 
by simply flowing over the particle that is to be 
ingested, grows to a certain limit of size, then di- 
vides into two more or less equal parts, each part 
becoming a new animal that goes on with its de- 



20 Insects and Disease 

velopment as did the parent form. This process 
of growth and division may go on for many gener- 
ations, but cannot continue indefinitely unless there 
is a conjugation of two separate individuals. This 
process of conjugation is just the opposite to that 
of division. Two amoeba flow together and be- 
come one. It seems to rejuvenate the organism so 
that it is able to go on with its division and thus 
fulfil its life-mission which is the same for these 
lowly animals as with the higher, that of perpetu- 
ating the species. 

Classes of Protozoa. The group or Phylum Pro- 
tozoa is divided into four smaller groups or classes. 
The amoeba belongs to the lowest of these, the 
Rhizopoda. Rhizopoda means "root-footed," and 
the name is applied to these animals because most 
of them move about by means of root-like processes 
known as pseudopodia or "false feet." This is 
by far the largest class and contains thousands of 
forms, mostly living in salt water but there are 
many fresh- water species. They are non-parasitic, 
but some of them by their presence in the body 
may cause such diseases as dysentery, etc. 

The next class which may be known as the whip- 
bearers (Mastigophora) includes those Protozoa 
that move by fine undulating processes called 
flagella. One of the common representatives of 



VU- *%^V ***** 



Fig. 7 — Typhoid Fever bacilli. (After 
Muir and Ritchie.) 




Fig. 8 — Amaba, showing the forms assumed by a single individual in 
four successive changes. (From Kellogg's Elementary Zool.) 




Fig. 9 — Euglina virdis. (After Saville Kent.) 




FlG. io — Spirocheta dultoni, x 4500. (After Brcinl and Carter.) 



Bacteria and Protozoa 21 

this class is the little green Euglena (Fig. 9), whose 
presence in standing ponds and puddles often im- 
parts a greenish color to the water. Then in the 
salt water near the surface there are often myri- 
ads of minute Noctiluca whose wonderfully phos- 
phorescent little bodies glow like coals of fire when 
the water is disturbed at night. Although this class 
contains fewer forms than the preceding some of 
these have within recent years been found to be of 
great importance because they live as parasites on 
man and other animals. The trypanosome whose 
presence in the blood and tissues of the patient 
causes that dreadful disease which ends in sleeping 
sickness belongs here as well as do several other 
similar kinds that produce serious troubles for va- 
rious mammals and birds. The Spirochaeta, about 
which there has been so much recent discussion, 
also belong here. These are simple spiral-like 
forms (Fig. 10), that are sometimes classed with 
the simple plants, bacteria, but Nuttall and others 
have shown very definitely that they should be 
classed with the simplest animals, the Protozoans. 
These are the cause of relapsing fevers in man 
and of several diseases of domestic animals. It is 
believed by certain eminent zoologists that when 
the germ that causes yellow fever is discovered it 
will be found to belong to this group. 



22 Insects and Disease 

The members of the class Infusoria, so called 
because they were early found to be abundant in 
various infusions, are characterized by numerous 
fine cilia or hair-like organs by means of which the 
organism moves about and procures its food. The 
well-known " slipper animalcule " (Paramoecium) 
(Fig. n), and the "bell-animalcule" (Vorticella) 
(Fig. 12) are two common representatives. The 
Paramoecia were the animals mostly used by Jen- 
nings in his wonderfully interesting experiments 
on the behavior of these lowly forms of life. He 
showed that they always reacted in a certain defi- 
nite way in response to particular stimuli, and he 
was led to believe that he could see "what must 
be considered the beginnings of intelligence and 
of many other qualities found in the higher ani- 
mals." A species of Vorticella was probably the 
first Protozoan that was ever observed. An old 
Dutch microscopist, Anton von Leeuwenhoek, in 
1675, while studying with lenses of his own manu- 
facture, discovered and described forms which un- 
doubtedly belong to this genus. Few if any of the 
Infusoria are pathogenic, although some are said 
to be associated with certain intestinal diseases 
both in man and the lower animals (Fig. 13). 

The last class, the Sporozoa, or the spore-forming 
animals, while small in the number of known spe- 





Fig. ii 



Fig. 12 



Fig. ii — Paramoecium. (From Kellogg's Elementary Zool.) 
Fig. 12 — V or lie ella, one individual with the stalk coiled, the other 
with the stalk extended. (From Kellogg's Elementary Zool.) 




Tig. 13 — Pathogenic Protozoa; a group of intestinal parasites. 
A, B, Megastoma entericum, C, Balantidum entozoon. (After Calkins.) 



Bacteria and Protozoa 23 

cies, only about three hundred kinds being known, 
is extremely important. A number of diseases in 
man and other animals are due to the presence of 
these Sporozoans, for they are all parasitic. Few 
if any animals are exempt from their attacks. 
They even attack other minute Protozoa. One 
hundred and fifty-seven species have been recorded 
as attacking insects, one hundred species attack 
birds, fifty- two reptiles, eighty crustaceans, twenty- 
two fish, and so through the list. Ten have been 
recorded as attacking man. In some instances 
the parasite is always present in the host and some 
hosts may harbor several different species of 
Sporozoa. 

Very little work had been done on this group of 
parasites prior to 1900. Since that time most of 
the species that we now know have been discov- 
ered, and within the last few years the life-histories 
of many of these have been worked out quite com- 
pletely. No other group of animals is being studied 
more to-day by both the physicians and biologists. 

The Sporozoa vary greatly in appearance, 
organization and life-history. They are so very 
plastic that they can adapt themselves readily to 
their various hosts, hence w T e have a great variety 
of forms. But they all agree in certain characters; 
all take their food and oxygen and carry on ex- 



24 Insects and Disease 

cretory processes by osmosis, i. e., through the 
body-wall ; all are capable of some kind of locomo- 
tion, some have one or more rlagella, others move 
by a pseudopod movement. Some are capable of 
moving from cell to cell in the body as do the 
white blood-corpuscles. They all agree in the pro- 
duction of spores — hence the name. 

At certain stages in their development the nu- 
cleus within the body of the organism divides again 
and again until there are a great many daughter 
nuclei, each accompanied by a small mass of proto- 
plasm, often inclosed in a little sac or cyst of its 
own. This is the process of spore-formation and 
we see that from a single individual we may have 
by division, not two animals as in the amoeba, but 
a score or more of them. The little cysts or 
capsules that inclose them enable them to resist 
without injury many vicissitudes that would other- 
wise destroy them. They may dry up or freeze or 
lie for a long time in the ground or water until the 
time comes when they are introduced into another 
host. 

The class Sporozoa is divided into five small 
groups or orders. Nearly all of these contain 
forms that are of more or less importance, but the 
ones that live in the blood -cells (H cento sporidiida) 
are of the most interest to us because the parasites 



Bacteria and Protozoa 25 

that cause the malarial fevers and various other 
diseases belong here. These are dependent on two 
hosts for their existence, the sexual generation 
usually occuring in an insect or other invertebrate 
and the asexual generation in some vertebrate. 




CHAPTER III 
TICKS AND MITES 

HE other group or Phylum of animals 
with which we will be particularly con- 
cerned is known as the Arthropoda, 
which means "jointed-feet" and in- 
cludes the crayfish, crabs, spiders, mites, ticks and 
insects. Of these only the last three are of inter- 
est to us now. It is customary to speak of spiders, 
mites and ticks as insects, but as they have four 
pairs of legs, instead of three pairs, in the adult 
stage, and as their bodies are not divided into 
three distinct regions as in the insects, they are 
placed in a different class. 

GENERAL CHARACTERS OF TICKS 

The ticks are all comparatively large, that is, they 

are all large enough to be seen with the unaided 

eye even in their younger stages and some grow to 

be half an inch long. When filled with blood the 

tough leathery skin becomes much distended often 

making the creature look more like a large seed 

26 



Ticks and Mites 27 

than anything else (Fig. 14). This resemblance is 
responsible for some of the popular names, such as 
" castor-bean tick," etc. 

The legs of most species are comparatively short, 
and the head is small so that they are often hardly 
noticeable when the body is distended. The suck- 
ing beak which is thrust into the host when the 
tick is feeding is furnished with many strong re- 
curved teeth which hold on so firmly that when one 
attempts to pull the tick away the head is often 
torn from the body and left in the skin. Unless 
care is taken to remove this, serious sores often 
result. 

Ticks are wholly parasitic in their habits. Some 
of them live on their host practically all their lives, 
dropping to the ground to deposit their eggs when 
fully mature. Others leave their host twice to 
molt in or on the ground. The female lays her 
eggs, 1,000 to 10,000 of them, on the ground or just 
beneath the surface. The young " seed-ticks " that 
hatch from these in a few days soon crawl up on 
some near-by blade of grass or on a bush or shrub 
and wait quietly and patiently until some animal 
comes along. If the animal comes close enough 
they leave the grass or other support and cling to 
their new-found host and are soon taking their first 
meal. Of course thousands of them are disap- 



28 Insects and Disease 

pointed and starve before their host appears, but 
as they are able to live for a remarkably long time 
without taking food their patience is often rewarded 
and the long fast ended. 

Those species which drop to the ground to molt 
must again climb to some favorable point and wait 
for another host on which they may feed for a 
while. Then they drop to the ground for a second 
molt and if they are successful in gaining a new 
host for the third time they feed and develop until 
fully mature and the female is ready to lay her 
eggs. The Texas fever tick, and some others, as 
we shall see, do not drop to the ground to molt but 
once having gained a host remain on it until ready 
to deposit their eggs. 

The young ticks have only six legs (Fig. 15) but 
after the first molt they all have eight. 

TICKS AND DISEASE 

Texas Fever. Ever since stockmen began driving 
southern cattle into states further north it has been 
noted that the roads over which they were driven 
became a source of great danger to northern cattle. 
Often 80% to 90% of the native cattle died after 
a herd of southern cattle passed through their 
region and the losses became so great that both 
state and national laws were passed prohibiting 




Fig. 14 — Castor Bean Tick (Ixodes ricinus) 
not fully gorged. 




Fig. 15 — Texas fever tick, just hatched; 
has only six legs. 




Fig. i 6 — Texas fever tick {Mar gar opus an- 
nulatus) young adult not fully gorged. 




Fig. 17 — Amblyomma variegatum several ticks belonging 
to this genus transmit Piroplasma which cause vari- 
ous diseases of domestic animals. 



Ticks and Mites 29 

the driving or shipping of southern cattle into 
northern states. 

But for years the cause of this fever, which came 
to be known as the Texas fever, was not known. 
The southern cattle themselves seemed healthy 
enough and it was difficult to understand how they 
could give the disease to the others. It was early 
noticed, too, that it was not necessary for the 
northern cattle to come in direct contact with the 
others in order to contract the disease. Indeed 
the disease was not contracted in this way at all. 
All that was necessary for them was to pass along 
the same roads or feed in the same pastures or 
ranges. Still more puzzling was the fact that these 
places did not seem to become a source of danger 
until some weeks after the southern cattle had 
passed over them and then they might remain 
dangerous for months. 

In 1886 Dr. Theobald Smith of the Bureau of 
Animal Industry, United States Department of 
Agriculture, found that the fever was caused by the 
presence in the infected cattle of a minute Sporo- 
zoan parasite (Piroplasma bigeminum). Further 
investigations and experiments proved conclusively 
that this parasite was transmitted from the infected 
to the well animal only by the common cattle tick 
now known as the Texas fever tick (Fig. 16). 



30 Insects and Disease 

The infection is not direct, that is, the tick does 
not feed on one host then pass to another carrying 
the disease germs with it. Unlike many other 
ticks the Texas fever tick does not leave its host 
until it is fully developed. When the female is full 
grown and gorged she drops to the ground and lays 
from 2,000 to 4,000 eggs which soon hatch into the 
minute " seed-ticks" which make their way to the 
nearest blade of grass or weed or shrub and 
patiently wait for the cattle to come along. 

If the mother tick had been feeding on an animal 
that was infected with the Texas fever parasite, 
her body was filled with the minute organisms of 
which some found their way into the eggs so that 
the young ticks hatching from them were already 
infected and ready to carry the infection to the first 
animal they fed upon. 

It took many years of hard patient work to 
learn all this, but the knowledge thus obtained 
cleared up much of the mystery in connection 
with the occurrence of the fever in the north and, 
as we shall see, suggested the possibility of other 
diseases being communicated in the same way. 

It was found that the southern cattle in the 
region where the ticks occur normally, usually 
have a mild attack of the disease when they are 
young and although they may be infected with the 



Ticks and Mites 31 

parasite all the rest of their lives it does not affect 
them seriously. These cattle are almost always 
infected with ticks, and when taken north where 
the ticks do not occur naturally and where the cat- 
tle are therefore non-immune, some of the mature 
ticks drop to the ground and lay their eggs which 
in a few weeks hatch out and are ready to infect 
any animal that passes by. The northern cattle 
not being used to the disease soon sicken and die. 

It is estimated that the annual loss due to this 
disease and the ravages of the tick in the United 
States is over $100,000,000, so of course most 
determined efforts are being made to stamp it out. 
Formerly various devices for dipping the tick- 
infested cattle into some solution that would kill 
the ticks were resorted to, but it was always ex- 
pensive and never very satisfactory. The immu- 
nizing of the cattle by inoculating them when they 
were young with infected blood has been practised. 
Very recent investigations have shown that it is 
possible and practicable to rid pastures of ticks 
by a system of feed-lots and pasture rotation. The 
aim is to have as many of the ticks as possible drop 
to the ground on land where they may be destroyed 
and to so regulate the use of the pasture that the 
ticks in all of them may eventually be left to starve. 

Several similar diseases of cattle, many of them 



32 Insects and Disease 

probably identical with Texas fever, occur in other 
parts of the world where the losses are sometimes 
appalling. Horses, sheep, dogs, and other animals 
are also affected with diseases caused by the same 
group of Protozoan parasites. Most of them have 
been shown to be transmitted by various species of 
ticks (Fig. 17) so that from an economical stand- 
point these little pests are becoming of prime im- 
portance. Not only do they transmit the disease 
germs that infect domestic animals but they are 
known to be responsible for at least two diseases 
of men, Rocky Mountain spotted fever and the 
relapsing fevers. 

Spotted Fever. The first of these is a disease that 
for some years has been puzzling the physicians in 
Idaho and Montana and other mountainous states. 
A few years ago certain observers recorded finding 
Protozoan parasites in the blood of those suffering 
from the disease, and although more recent in- 
vestigations have failed to confirm these particular 
observations it is now quite generally believed that 
the disease is caused by some such parasite and that 
the organism is transferred from one host to an- 
other by certain species of ticks that live on wild 
mammals of the region where the disease exists. 
Dr. H. T. Ricketts, who has made a special study 
of the disease, has shown: 



Ticks and Mites 33 

"1. That the period of activity of the disease is lim- 
ited to the season during which the adult female and 
male ticks attack man. 

"2. That in practically all cases of this disease it 
can be shown that the patient has been bitten by a 
tick. 

"3. That the period between the tick bite and the 
onset of the disease in the many animals he has ex- 
perimented with corresponds very closely to this period 
as observed in man. 

"4. That infected ticks are to be found in the lo- 
cality where the disease occurs. 

"5. That the virus of spotted fever is very inti- 
mately associated with the tissues of the tick's body as 
is shown by the fact that the female passes the infection 
on to her young through her eggs, and further, by the 
observation that in either of the two earlier stages of 
the life cycle the disease may be contracted by biting 
a sick animal and communicated to other animals 
after molting or even after passing through an inter- 
mediate stage." 

Professor R. A. Cooley of Montana, from whose 
report the above quotation is taken, has also made 
studies of the habits of the tick and believes there 
can be no doubt that it is the disseminator of the 
disease. 

Relapsing Fever. The relapsing fever is an in- 
fectious disease or possibly a group of closely re- 



34 Insects and Disease 

lated infectious diseases occurring in various parts 
of the world. Occasionally it is introduced into 
America, but it does not seem to spread here. It 
has been shown that the disease is communicated 
from one person to another by means of blood- 
sucking insects. In Central Africa where the 
disease is very prevalent a certain common tick 
(Ornithodoros moubata) (Fig. 18) is known to 
transmit the disease. This tick lives in the resting 
places and around the huts of the natives and has 
habits very similar to the bedbug of other climes, 
feeding at night and hiding during the day. 
It attacks both man and beast and is one of the 
most dreaded of all the African pests. 

Nathan Bank, our foremost authority on ticks, 
in summing up the evidence against them says : 

"It is therefore evident that all ticks are potentially 
dangerous. Any tick now commonly infesting some 
wild animal, may, as its natural host becomes more 
uncommon, attach itself to some domestic animal. 
Since most of the hosts of ticks have some blood- 
parasites, the ticks by changing the host may trans- 
plant the blood-parasites into the new host producing, 
under suitable conditions, some disease. Numerous 
investigators throughout the world are studying this 
phase of tick-life, and many discoveries will doubtless 
signalize the coming years." 



Ticks and Mites 35 

MITES 

The mites are closely related to the ticks, and al- 
though none of them has yet been shown to be 
responsible for the spread of any disease their 
habits are such that it would be entirely possible 
for some to transmit certain diseases from one 
host to another, from animal to animal, from ani- 
mal to man, or from man to man. A number of 
these mites produce certain serious diseases among 
various domestic animals and a few are responsi- 
ble for certain diseases of men. 

Face-mites. Living in the sweat-glands at the 
roots of hairs and in diseased follicles in the skin 
of man and some domestic animals are curious 
little parasites that look as much like worms as 
mites (Fig. 19). Such diseased follicles become 
filled with fatty matter, the upper end becomes 
hard and black and in man are known as black- 
heads. If one of these blackheads is forced out and 
the fatty substance dissolved with ether the mites 
may be found in all stages of development. The 
young have six legs, the adult eight. The body is 
elongated and transversely wrinkled. In man 
they are usually found about the nose and chin 
and neck where they do no particular harm except 
to mar the appearance of the host and to indicate 



36 Insects and Disease 

that his skin has not had the care it should have. 
Very recently certain investigators have found that 
the leprae bacilli are often closely associated with 
these face mites and believe that they may possibly 
aid in the dissemination of leprosy. It is also 
thought that they may sometimes be the cause of 
cancer, but as yet these theories have not been 
proven by any conclusive experiment. 

In dogs and cats these same or very similar 
parasites cause great suffering. In bad cases the 
hair falls out and the skin becomes scabby. 
Horses, cattle and sheep are also attacked. The 
disease caused by these mites on domestic animals 
is not usually considered curable except in its very 
early stages when salves or ointments may help 
some. 

Itch-mites. "As slow as the seven-years' itch" 
is an expression, the meaning of which many could 
appreciate from personal experience, for it certainly 
seemed to take no end of time to get rid of the itch 
once it was contracted. Just why seven years 
should have been set for the limit of the disease is 
not clear, for if the little roundish mites that cause 
the disease live for seven years on a host they are 
not going to move out voluntarily even if their 
seven-year lease has expired. 

The minute whitish mites (Fig. 20) that cause 




Fig. iS—Ornithodorus moubata, the Tick that 
Transmits Relapsing Fever. From Boyce's 
" Mosquito or Man." 




Fig. 19 — The follicle mite (Demodex follicu- 
lorum). (After Murray.) 



Kft 






40fik 



• * s 



Fig. 20 — Itch-mite (Sarcoptes scabiei). (After 
Murray.) 




Fig. 21 — Harvest-mites or "jiggers." (Leptus irritaus 
and L. americanus.) (After Riley.) 



Ticks and Mites 37 

this disgusting disease are barely visible to the 
naked eye. They are usually very sluggish but 
become more active when warmed. They live in 
burrows just beneath the outer layer of skin, 
sometimes extending deeper and causing most 
intense itching. As the female burrows, she lays 
her eggs from which come the young mites that are 
to spread the infection. Various sulphur ointments 
and washes are used as remedies. Cleanliness will 
prevent infection. 

Closely related to the itch-mite of man (Sarcoptes 
scabiei) are several kinds attacking domestic ani- 
mals, causing mange, scab, etc. The variety infest- 
ing horses burrows in the skin and produces sores 
and scabs, and is a source of very great annoyance. 
These mites may also migrate to man. Tobacco 
water and sulphur ointments are used as remedies. 

Horses and cattle are also infested by other 
mites (Psoroptes communis) which cause the com- 
mon mange. These do not burrow into the skin 
but live outside in colonies, feeding on the skin and 
causing crusts or scabs. The inflammation causes 
the animal to scratch and rub constantly and often 
causes the loss of much of the hair. 

Harvest-mites. A score or more of different va- 
rieties of mites cause many other diseases of do- 
mestic animals, such as the scab of sheep and hogs 



38 Insects and Disease 

and chickens, various other manges of the horses 
and cattle and dogs, etc. But we need to call atten- 
tion to just one more example, that of the harvest- 
mites or jiggers (Fig. 21). Professor Otto Lugger, 
from whose report on the Parasites 0} Man and 
Domestic Animals most of these notes in regard to 
the mites are taken, thus feelingly refers to this pest. 

"About the very worst pests of man and domesti- 
cated animals are the Harvest-bugs, Red-bugs or Jig- 
gers. . . . Men and animals passing through low herb- 
age that harbors them are attacked by these pests, which, 
whenever they succeed in finding a host, burrow in and 
under the skin, causing intolerable itching and sores, the 
latter caused by the feverish activity of the finger-nails 
of the host, if that should be a man, whose energy in 
scratching, apparently, cannot be controlled and who is 
bound forcibly to remove the intruders. The writer 
has been there! Those who have ever passed through 
meadows infested with red-bugs will remember the oc- 
casion." 

Horses, cattle, dogs and cats and other animals 
suffer also. Again sulphur ointments are the best 
remedies. 

"The normal food of these mites must, apparently, 
consist of the juices of plants, and the love of blood 
proves ruinous to those individuals which get a chance 



Ticks and Mites 39 

to indulge it. For, unlike the true chigoe, the female 
of which deposits eggs in the wound she makes, these 
harvest-mites have no object of the kind, and when 
not killed at the hands of those they torment they soon 
die victims to their sanguinary appetite." 




CHAPTER IV 

HOW INSECTS CAUSE OR CARRY 
DISEASE 

T has been estimated that there are 
about four thousand species or kinds of 
Protozoans, about twenty-five thou- 
sand species of Mollusks, about ten 
thousand species of birds, about three thousand 
five hundred species of mammals, and from two 
hundred thousand to one million species of insects, 
or from two to five times as many kinds of insects 
as all other animals combined. 

Not only do the insects preponderate in number 
of species, but the number of individuals belonging 
to many of the species is absolutely beyond our 
comprehension. Try to count the number of little 
green aphis on a single infested rose-bush, or on a 
cabbage plant ; guess at the number of mosquitoes 
issuing each day from a good breeding-pond ; es- 
timate the number of scale insects on a single 
square inch of a tree badly infested with San Jose 

scale ; then try to think how many more bushes or 

40 



How Insects Cause or Carry Disease 41 

trees or ponds may be breeding their millions just 
as these and you will only begin to comprehend the 
meaning of this statement. 

As long as these myriads of insects keep in what 
we are pleased to call their proper place we care 
not for their numbers and think little of them ex- 
cept as some student points out some wonderful 
thing about their structure, life-history or adapta- 
tions. But since the dawn of history we find ac- 
counts to show that insects have not always kept 
to their proper sphere but have insisted at various 
times and in various ways in interfering with man's 
plans and wishes, and on account of their exces- 
sive numbers the results have often been most dis- 
astrous. 

Insects cause an annual loss to the people of the 
United States of over $1,000,000,000. Grain fields 
are devastated ; orchards and gardens are destroyed 
or seriously affected ; forests are made waste places 
and in scores of other ways these little pests which 
do not keep in their proper places are exacting this 
tremendous tax from our people. 

These things have been known and recognized 
for centuries, and scores of volumes have been 
written about the insects and their ways and of 
methods of combating them. 

But it is only in recent years that we have begun 



42 Insects and Disease 

to realize the really important part that insects 
play in relation to the health of the people with 
whom they are associated. Dr. Howard estimates 
that the annual death rate in the United States 
from malaria is about twelve thousand, entailing 
an annual monetary loss of about $100,000,000, to 
say nothing of the suffering and misery endured by 
the afflicted. All this on account of two or three 
species of insects belonging to the mosquito genus 
Anopheles. 

Yellow fever, while not so wide-spread, is more 
fatal and therefore more terrorizing. Its presence 
and spread are due entirely to a single species of 
mosquito. Flies, fleas, bedbugs, and many other 
insects have been shown to be intimately connected 
with the spread of several other most dreaded 
diseases, so it is no wonder that physicians, ento- 
mologists and biologists are studying with utmost 
zeal many of these forms that bear such a close 
relation not only to our welfare and comfort but 
to our lives as well. 

It would be out of place to try to give here even a 
brief outline of the classification of insects, such as 
may be found in almost any of the many books 
devoted to their study. 

The most generally accepted classification di- 
vides the insects into nineteen orders; as the 



How Insects Cause or Carry Disease 43 

Coleoptera, containing the beetles; the Lepidop- 
tera, containing the butterflies and moths; the Hy- 
menoptera containing the bees, ants and wasps, 
etc. Four or five of these orders will be of more or 
less interest to us. 

The order Diptera, or two-winged flies, is the 
most important because to this belong the mos- 
quitoes which transmit malaria and yellow fever, 
and the house-fly that has come into prominence 
since it has been found to be such an important 
factor in the distribution of typhoid and other 
diseases. 

FLIES 

The order Diptera is divided into sixty or more 
families, many of which contain species of con- 
siderable economic importance. For our present 
consideration the flies may be divided into two 
groups or sections: those with their mouth-parts 
fitted for piercing such as the mosquito and horse- 
fly, and those with sucking mouth-parts such as the 
house-fly, blow-fly and others. 

Some of the species belonging to the first group 
are among the most troublesome pests not only of 
man but of our domestic animals as well. Next 
to the mosquitoes the horse-flies (Fig. 22) are per- 
haps the best known of these. There are several 
species known under various names, such as gad- 



44 Insects and Disease 

fly, breeze-fly, etc. They are very serious pests of 
horses and cattle, sometimes also attacking man. 
Their strong, sharp, piercing stylets enable them to 
pierce through the toughest skin of animals and 
through the thin clothing of man. The bite is very 
severe and irritating, and as the flies sometimes 
occur in great numbers the annoyance that they 
cause is often very great indeed. It has often been 
claimed that these flies as well as the stable-fly and 
others carry the anthrax bacillus on their proboscis 
from one animal to another, and although this may 
not have been definitely proven the evidence is 
strong enough to make a very good case against the 
accused. It is interesting to note in this connection 
that anthrax, a very common disease among the 
domestic animals and one which may attack man 
also, was the first disease to be shown to be of 
bacterial origin. It was only about thirty-five 
years ago that the investigations of Koch and 
Pasteur demonstrated that the presence of this 
particular germ {Bacillus anthracis) was the cause 
of the disease, and it was early recognized that such 
biting flies may be important factors in the spread 
of the disease. 

The stable-fly (Fig. 23) (Stomoxys calcitrans) 
which looks very much like the house-fly and, as 
will be noted later, frequently enters houses, is 




Fig. 22 — Horse-fly (Tabanus 
pnnctifer). 




Fig. 23 — Stable-fly (Stomoxys calcitrans). 





Fig. 24 



Fig. 2 = 




Fig. 26 



Fig. 24— A Black-fly {Simulium sp.). (From Relief's Amer. 
Insects.) 

Fig. 25 — Screw-worm fly (Chrysomyia macellarL). 
Fig. 26 — Blow-fly (Calliphora vomitoria). 



How Insects Cause or Carry Disease 45 

often an important pest of horses and cattle. Its 
blood-sucking habit makes it quite possible that 
it too may be concerned in carrying anthrax and 
other diseases. 

In a later chapter it will be shown how the tse- 
tse-fly, which is somewhat like the stable-fly, is 
responsible for the spread of the disease known 
as the sleeping sickness. This disease is caused 
by a Protozoan parasite, a trypanosome, which is 
transmitted from one host to another by the tse- 
tse-fly. 

In Southern Asia and in parts of Africa there is a 
very serious disease of horses known as surra which 
is caused by a similar parasite (Trypanosoma 
evansi). This parasite attacks horses, mules, 
camels, elephants, buffaloes and dogs, and has been 
recently imported into the Philippines. It is sup- 
posed that flies belonging to the same genus as the 
horse-fly (Tabanus and others), and the stable-fly 
(Stomoxys) and the horn-fly (Hcematobia) are re- 
sponsible for the spread of the disease. 

Nagana is one of the most serious diseases of 
domestic animals in Central and Southern Africa. 
In some sections it is almost impossible to keep any 
kind of imported animals on account of this disease 
which is caused by a parasite (Trypanosoma 
brucei) similar to the one causing surra. This 



46 Insects and Disease 

parasite is to be found in several different kinds of 
native animals which seem to be practically im- 
mune but are always a source of danger when other 
animals are introduced. Two or three species of 
tsetse-flies are responsible for the transmission of 
this disease. 

Another group of flies much smaller but more 
numerous and much more insistent are the black- 
flies or buffalo-gnats (Fig. 24). For more than a 
century these little flies have been recognized as 
among the most serious pests of stock, particularly 
in the south where, besides the actual loss by death 
of many animals yearly, the annoyance is so great 
as to sometimes make it impossible to work in the 
field. Human beings are often attacked, and as 
the bite is poisonous and very painful great suffer- 
ing may result and cases of deaths from such 
bites have been reported. 

Belonging to another family, and smaller, but 
much like the buffalo-gnat in habits, are the minute 
little "punkies" or "no-see-ums" which sometimes 
occur in great swarms in certain regions where 
they make life a burden to man and beast. While 
it has not been shown that either the buffalo-gnats 
or the punkies are responsible for the transmission 
of any disease, their habits of feeding on so many 
different kinds of wild and domestic animals as 



How Insects Cause or Carry Disease 47 

well as on man makes it possible for them to act 
as carriers of parasites that might under proper 
conditions become of serious importance. Then, 
too, the irritation caused by the bites of these in- 
sects usually causes scratching which may result 
in abrasions of the skin that open the way for 
various harmful germs, particularly those causing 
skin diseases. 

Coming now to the group containing the house- 
flies and related forms we find a number that are 
of interest on account of the suffering that they 
may cause, particularly in their larval stages. 

The screw-worm flies (Chrysomyia macellaria) 
are among the most common and important of 
these (Fig. 25). These "gray flies," as they are 
sometimes called, lay a mass of three or four 
hundred eggs on the surface of wounds. The 
larvae which in a few hours hatch from these make 
their way directly into the wound where they feed 
on the surrounding tissue until full grown when 
they wriggle out and drop to the ground where 
they transform to the pupa and later to the adult 
fly. Of course their presence in the wounds is 
very distressing to the infected animal, and great 
suffering results. Slight scratches that might other- 
wise quickly heal often become serious sores be- 
cause of the presence of these larvae. 



4^ Insects and Disease 

Many cases are recorded of these flies laying 
their eggs in the ears or nose of children or of per- 
sons sleeping out of doors during the day. Espe- 
cially is this apt to occur if there are offensive dis- 
charges which attract the fly. In such cases the 
larvae burrow into the surrounding tissues, de- 
vouring the mucous membranes, the muscles and 
even the bones, causing terrible suffering and 
usually, death. The larvae in such situations may 
be killed with chloroform and, if the case is at- 
tended to before they have destroyed too much of 
the tissues, recovery usually occurs. 

The blow-flies (Fig. 26) (Calliphora vomitoria) 
and the bluebottle flies (Fig. 27), (Lucilia spp.) 
and the flesh-flies (Fig. 28) (Sarcophaga spp.) all 
have habits somewhat like the screw-worm fly. 
Any of them may lay their eggs in wounds on man 
or animals with the same serious results. 

The flesh-fly instead of laying eggs deposits the 
living larvae upon meat wherever it is accessible, 
and as these develop with astonishing rapidity they 
are able to consume large quantities of flesh in a 
remarkably short time. In this way they may be 
of some importance as scavengers, but it is better 
to get rid of the waste in other ways than to leave 
it for a breeding- place for flies that are capable of 
causing so much damage and suffering. 



How Insects Cause or Carry Disease 49 

Not infrequently the larvae of certain flies are 
to be found in the alimentary canal where as a rule 
they do no particular damage. Altogether the 
larvae of over twenty different species of flies have 
been found in or expelled from the human in- 
testinal canal. In Europe, the majority of these 
larvae belong to a fly which looks very much like 
the house-fly except that it is somewhat smaller 
and so is often known as "the little house-fly' ' 
(Fig. 29) (Homalomyia canicularis). The same 
species is very common in the United States, fre- 
quently occurring in houses. Under certain con- 
ditions it may even be more abundant than the 
house-fly. It is believed that the larvae in the in- 
testinal canal come from eggs that have been de- 
posited on the victim while using an outdoor privy 
where the flies are often very abundant. Instances 
are also on record where these larvae have been 
discharged from the urethra. 

Another fly (Ochromyia anthropophaga) occur- 
ring in the Congo region has a blood-sucking larvae 
which is known as the Congo floor-maggot. The 
fly which is itself not troublesome deposits its eggs 
in the cracks and crevices of the mud floors of the 
huts. The larvae which hatch from these crawl out 
at night and suck the blood of the victim that may 
be sleeping on the floor or on a low bed. 



50 Insects and Disease 

BOT-FLIES 

Another group of flies known as the bot-flies 
(Fig. 30) have their mouth-parts rudimentary or 
entirely wanting so of course they themselves can- 
not bite or pierce an animal. Nevertheless they 
are the source of an endless amount of trouble to 
stockmen and sometimes even attack man. Al- 
though these flies cannot bite, the presence of even 
a single individual may be enough to annoy a horse 
almost to the end of endurance. Horses seem to 
have an instinctive fear of them and will do all in 
their power to get rid of the annoying pests. 

The eggs of the house bot-fly are laid on the 
hair of the legs or some other part of the body. 
The horse licks them off and they hatch and 
develop in the alimentary canal of their host. 
Sometimes the walls of the stomach may be 
almost covered with them thus of course seriously 
interfering with the functions of this organ. When 
full grown the larvae pass from the host and com- 
plete their transformation in the ground. 

The bot-flies of cattle or the oxwarbles (Fig. 31) 
gain an entrance into the alimentary canal in the 
same way, that is, by the eggs being licked from the 
hairs on the body where they have been laid by 
the adult fly. But instead of passing on into the 




Fig. 27 — Bluebottle fly {Lucilia sericata). 




Fig. 28 — Flesh-fly (Sarcophaga sp). 




Fig. 29 — "The little house-fly' 
(Homalomyia canicularis) . 



Fig. 30 — Horse bot-fly (Gastrophilus 
equi). 




Fig. 31 — Ox warble-fly (Hypoderma 
lineata). 



Fig. 32 — Sheep bot-fly (Gastrophilus 
nasalis). 



How Insects Cause or Carry Disease 51 

stomach they collect in the esophagus and later 
make their way through the walls of this organ and 
through the tissues of the body until they at last 
reach a place along the back just under the skin. 
Here as they are completing their development 
they make more or less serious sores on the backs 
of the infested animals. The hides on such ani- 
mals are rendered nearly valueless by the holes 
made by the larvae. When fully mature they drop 
to the ground and complete their transformations. 

The sheep bot-flies (Fig. 32) lay their eggs in 
the nostrils of sheep. The larvae pass up into the 
frontal sinuses where . they feed on the mucus, 
causing great suffering and loss. Many other 
species of animals are infested with their own par- 
ticular species of bots. Several instances are 
recorded where the oxwarble has occurred in man, 
always causing much suffering and sometimes 
death. 

One or more species of bot-flies occurring in the 
tropical parts of America frequently attack man. 
The early larval stage soon after it has entered the 
skin is known as the Ver macaque. Later stages 
as torcel or Berne. The presence of the larvae pro- 
duces very painful and troublesome sores. It is 
supposed that the adult flies (one species of which 
is Dermatobia cyaniventris) lay their eggs on the 



52 Insects and Disease 

skin which the larvae penetrate as soon as they 
hatch. It has also been suggested that they might 
reach the subcutaneous tissue by migrating from 
the alimentary canal as do some of the other bot- 
flies. A very serious eye disease, Egyptian opthal- 
mia, is known to be spread by the house-flies and 
others. These flies are often abundant about the 
eyes, especially of children suffering from this 
disease. It is suspected that certain small flies 
(Oscinidae) in the southern part of the United 
States are responsible for the spread of disease 
known as "sore eye." 

FLEAS 

The fleas used to be considered as degenerate 
Diptera and were placed with that group but they 
are now classed as a separate order (Siphonaptera). 
Within recent years these little pests have come 
into special prominence on account of their im- 
portance in connection with the spread of the 
plague. The fact that they are so abundant every- 
where and that they will so readily pass from one 
host to another makes the possibility of their 
spreading infectious diseases very great. Besides 
the kinds that are concerned in the transmission 
of plague, which are discussed in another chap- 
ter, there are many other kinds infesting various 



How Insects Cause or Carry Disease 53 

wild and domesticated animals and a few attack- 
ing birds. 

One of the most important of these is the jigger- 
flea or chigoe (Dermatophilus penetrans, Fig. 33). 
Various other names such as chigger-flea, sand- 
flea, jigger, chigger are also applied to this insect 
as well as to a minute red mite that burrows into 
the skin in much the same way as the female of 
the flea. So although they are entirely different 
creatures you can never tell from the common 
name, whether it is the flea or the mite that is be- 
ing referred to. Both the male and female jigger- 
fleas feed on the host and hop on or off as do other 
fleas, but when the female is ready to lay eggs 
(Fig. 34), she burrows into the skin. Her pres- 
ence there causes a swelling and usually an ulcer 
which often becomes very serious, especially if the 
insect should be crushed and the contents of the 
body escape into the surrounding tissue. 

These little pests are found throughout tropical 
and subtropical America and have been introduced 
into Africa and from there have spread to India 
and elsewhere. They attack almost all kinds of 
animals as well as many birds, being of course a 
source of great annoyance and no inconsiderable 
loss. They are more apt to attack the feet of men, 
especially those who go barefooted. Sometimes 



54 Insects and Disease 

they occur in such numbers as to make great 
masses of sores. 

On account of being such general feeders they 
are difficult to control, but some relief may be ob- 
tained by keeping the houses and barns as free as 
possible from dirt and rubbish and by sprinkling 
the breeding-places of the pest with pyrethrum 
powder or carbolic water. Those that gain an en- 
trance into the skin should be cut out, care being 
taken to remove the insect entire. 

BEDBUGS 

In the order Hemiptera, or the true "bugs" in 
an entomological sense, we find a few forms that 
may carry disease. The bedbug (Fig. 35) (Cimex 
lectularis) has been accused of transmitting plague, 
relapsing fever and other diseases. Very recent 
investigations show that the common bedbug of 
India (Cimex rotundatus) harbors the parasite 
that causes the disease known as kala azar, and 
there is no doubt that it transmits the disease. 

LICE 

The sucking lice (Fig. 36) which also belong to 
this order are suspected of carrying some of these 
same diseases. It is thought that the common 




Fig. 33 — Chigo or jigger-flea, male {Dermatoph- 
ilus penetrans). (After Karsten.) 




Fig. 34 — Chigo, female distended with eggs. 
(After Karsten.) 




Fig. 35— Bedbug (Cimex 


leciularis) . 


^ 1 ** -, ^p^^^^ 8 




#<r' :, i 


^v 


v /*wa3r '"' '~~~^? 


£3 


//C ~ if'^Wr^i^ 




' $&? » ' '*^5*' c, - r - ~1& 




$:':&?WjVi%, 








wj^j ■ i ■■' '• 'iJaJ$ 










f 





Fig. 36 — Body-louse (Pediculus vestimenti). 
(From drawing by J. H. Paine.) 



How Insects Cause or Carry Disease 55 

louse on rats (Hamatopinus spinulosus) is respon- 
sible for the spread from rat to rat of a certain 
parasite. (Trypanosoma lewisi), which, however, 
does not produce any disease in the rats, but if 
they are capable of acting as alternative hosts 
for such parasires, it is quite possible that they 
may also carry disease-producing forms. 

HOW INSECTS MAY CARRY DISEASE GERMS 

Insects may carry the germs or parasites which 
cause disease in a purely mechanical or accidental 
way, that is, the insect may in the course of its 
wanderings or its feeding get some of the germs on 
or in its body and may by chance carry these to 
the food, or water, or directly to some person who 
may become infected. Thus the house-fly may 
carry the typhoid germs on its feet or in its body 
and distribute them in places where they may enter 
the human body. 

Several other flies as well as fleas, bedbugs, 
ticks, etc., may also carry disease germs in this 
mechanical way. While this method of transmis- 
sion is just as dangerous as any other, and possi- 
bly more dangerous because more common, an- 
other method in which the insect is much more 
intimately concerned is more interesting from a 
biological standpoint at least and will be discussed 



56 Insects and Disease 

more fully in the chapters on malaria, yellow fever 
and elephantiasis. 

In these cases the insect is one of the necessary 
hosts of the parasite, which cannot go on with its 
development or pass from one patient to another 
unless it first enters the insect at a certain stage of 
its life-history. 



ECLECTIC SERIES. 



LESSON VII. 




tick'ling 
neck 

s</t;ret 
legg 
ope 

tO«g 

cboo§e 

nod 
six 



jpread be lieve' 

BABY-BYE. 

1. Baby-Bye, 
Heru 's . a fly ; 
We wilt watch him, you and }. 

How be crawls 

Up the walls, 

Yet he never falls! 
I believe with six such le<rs 
You and I could walk on eggs, 

Thoro ho goes 

On his toes. 

Tickling Baby's nose. 



Fig. 37 — One use for the house-fly. 




CHAPTER V 

HOUSE-FLIES OR TYPHOID-FLIES 

HE page shown in Fig. 37 was copied from 
one of our old second readers and shows 
something of the spirit in which we used 
to regard the house-fly. A few of them 
were nice things to have around to make things 
seem "homelike." Of course they sometimes be- 
came too friendly during the early morning hours 
when we were trying to take just one more little nap 
or they were sometimes too insistent for their por- 
tion of the dinner after it had been placed on the 
table, but a screen over the bed would help us out 
a little in the morning and a long fly-brush cut 
from a tree in the yard or made of strips of paper 
tacked to a stick or, still more fancy, made of long 
peacock plumes, would help to drive them from 
the table. Those that were knocked into the coffee 
or the cream could be fished out; those that went 
into the soup or the hash were never missed ! 

Not only were the flies regarded as splendid 
things with which to amuse the baby, but they 

57 



58 Insects and Disease 

were thought to be very useful as scavengers as 
they were often seen feeding on all kinds of refuse 
in the yard. Then, too, they seemed to be cleanly 
little things, for almost any time some of them 
could be seen brushing their heads and bodies 
with their legs and evidently having a good 
clean-up. More than that it never occurred to 
us that it would be possible to get rid of them 
even should it be thought advisable, for they came 
from "out doors," and who could kill all the flies 
"out doors"? 

Fortunately, or otherwise, these halcyon days 
have gone by and the common, innocent, friendly 
little house-fly ; s now an outcast convicted of 
many crimes and accused of a long list of others 
(Fig. 38). 

Its former friends have become its sworn ene- 
mies. The foremost entomologist of the land has 
suggested that we even change its name and give 
it one that would be more suggestive of the ab- 
horence with which we now look upon it. 

And all these changes have come about because 
science has turned the microscope on the house- 
fly and men have studied its habits. We know 
now that as the fly is "tickling baby's nose" it 
may be spreading there where they may be in- 
haled or where they may be taken into the baby's 




Fig. 38 — The house-fly (Musca domestica). 



House-Flies or Typhoid-Flies 59 

mouth thousands of germs some of which may 
cause some serious disease. We know that as 
they are buzzing about our faces while we are 
trying to sleep they may, unwittingly, be in the 
same nefarious business, and we know that as they 
sip from our cups with us or bathe in our coffee 
or our soup or walk daintily over our beefsteak 
or frosted cake they are leaving behind a trail of 
filth and bacteria, and we know that some of these 
germs may be and often are the cause of some of 
our common diseases. As the typhoid germs are 
very often distributed in this way, Dr. Howard 
has suggested that the house-fly shall be known 
in the future as the typhoid-fly, not because it is 
solely responsible for the spread of typhoid, but 
because it is such an important factor in it and 
is so dangerous from every point of view. The 
names " manure fly" and " privy fly" have also 
been suggested and would perhaps serve just as 
well, as the only object in giving it another name 
would be to find a more repulsive one to remind 
us constantly of the filthy and dangerous habits 
of the fly. 

STRUCTURE 

In order that we may better understand why 
it is that the house-fly is capable of so much 
mischief, let us consider briefly a few points in 



60 Insects and Disease 

regard to its structure, its methods of feeding and 
its life-history. 

The large compound eyes are the most con- 
spicuous part of the head (Fig. 39). In front, 
between the eyes, are the three-jointed antennae, 
the last joint bearing a short, feathery bristle. 
From the under side of the head arises the long, 
fleshy proboscis (Fig. 40). When this is fully 
extended it is somewhat longer than the head; 
when not distended and in use it is doubled back 
in the cavity on the under side of the head. About 
half-way between the base and the middle is a 
pair of unjointed mouth-feelers (maxillary palpi). 
At the tip are two membranous lobes (Fig. 41) 
closely united along their middle line. These are 
covered with many fine corrugated ridges, which 
under the microscope look like fine spirals and 
are known as pseudotracheae. Thus it will be seen 
that the house-fly's mouth-parts are fitted for suck- 
ing and not for biting. Its food must be in a 
liquid or semi -liquid state before it can be sucked 
through the tube leading from the lobes at the tip 
up through the proboscis and on into the stomach. 
If the fly wishes to feed on any substance such as 
sugar, that is not liquid, it first pours out some 
saliva on it and then begins to rasp it with the 
rough terminal lobes of the proboscis, thus re- 




Pig. 39 — Head of house-fly showing 
eyes, antennae and mouth-parts. 




Fig. 40 — Proboscis of house- 
fly, side view. 




Fig. 41 — Lobes at end of proboscis of house-fly showing corru- 
gated ridges. 




Fig. 42 — Wing of house-fly. 



House-Flies or Typhoid-Flies 61 

ducing the food to a consistency that will enable 
the fly to suck it up. Many people think that 
house-flies can bite and will tell you that they 
have been bitten by them. But a careful examina- 
tion of the offender, in such instances, will show 
that it was not a house-fly but probably a 
stable-fly, which does have mouth-parts fitted for 
piercing. 

The thorax bears the two rather broad, mem- 
branous wings (Fig. 42) which have characteristic 
venation. Three of these veins end rather close 
together just before the tip of the wing, the pos- 
terior one of the group being bent forward rather 
sharply a short distance from the tip. The stable - 
fly has this vein slightly curved forward but not 
nearly so conspicuously (Fig. 43). 

Nearly all the other flies that are apt to be mis- 
taken for the house-fly do not have this vein 
curved forward. The wings, although apparently 
bare, are covered with a fine microscopic pubes- 
cence. Among these fine hairs on the wing as well 
as among similar fine ones and coarser ones all 
over the body, particles of dust and dirt or filth 
(Fig. 44) or, what interests us more just now, 
thousands of germs may find a temporary lodg- 
ment and later be scattered through the air as the 
insect flies. Or they may get on our food as the 



62 Insects and Disease 

fly feeds or while it rests and combs its body with 
the rows of coarse hairs on its legs. 

The legs are rather thickly covered with coarse 
hairs or bristles and with a mat of fine, short 
hairs. On some of the segments the larger hairs 
are arranged in rows and are used as a sort of 
comb with which the fly combs the dirt from the 
rest of its body. The last segment (Fig. 45) of 
the leg bears at its tip a pair of large curved claws 
and a pair of membranous pads known as the 
pulvillae. On the under side of the pulvillae are 
innumerable minute secreting hairs (Fig. 46) by 
means of which the fly is able to walk on the wall 
or ceiling or in any position on highly-polished 
surfaces. 

HOW THEY CARRY BACTERIA 

These same little pads, with their covering of 
secreting hairs, are perhaps the most dangerous 
part of the insect for they cannot help but carry 
much of the filth over or through which the fly 
walks, and as this may be well stocked with germs 
the danger is at once apparent. 

As the result of a series of carefully planned 
experiments it has been demonstrated that the 
number of bacteria on a single fly may range all 
the way from 550 to 6,600,000 with an average for 
the lot experimented with of about one and one- 




Fig. 43 — Wing of Stable-fly (Stomoxyj calcitrans). 




Fig. 44 — Wing of house-fly showing particles of dirt adher- 




Fig. 45 — Last three segments of leg of house-fly showing th 
claws, the pulvillae and the hairs on the legs. 




Fig. 46 — Foot of house-fly showing claws, hairs, pul- 
villae and the minute clinging hairs on the pulvilla;. 




Fig. 47 — Larva of house-fly. 



House-Flies or Typhoid-Flies 63 

fourth million bacteria to each fly. Now where 
do all these bacteria come from? Necessarily 
from the place where the fly breeds or where 
it feeds. 

LIFE-HISTORY AND HABITS 

The eggs of the house-fly may be laid on almost 
any kind of decaying or fermenting material. If 
this is kept moist and a proper temperature main- 
tained the larvae or maggots (Fig. 47) that hatch 
from the eggs may develop. As a rule, however, 
these requirements are found only under certain 
conditions and are ordinarily found only in ma- 
nure heaps or in privy vaults or latrines. All ob- 
servers agree that the female fly prefers to deposit 
her eggs in horse manure when this can be found 
and when this is piled in heaps in the barn-yard 
(Fig. 48) or in the field the heat caused by the 
decay and fermentation makes ideal conditions 
for the development of the larvae. Cow manure 
may serve as a breeding-place to a limited extent. 
The flies are immediately attracted to human ex- 
crement and breed freely in it when opportunity 
offers. Decaying vegetables or fruit, fermenting 
kitchen refuse and other materials sometimes also 
serve as breeding-places. 

In suitable places in warm weather the eggs will 



64 Insects and Disease 

hatch in from eight to twelve hours and the larvae 
will become fully developed in from eight to four- 
teen days. They then change to pupae (Fig. 50) 
in which stage they may remain for another eight 
to twenty days when the adult flies will emerge. 
These figures must necessarily be indefinite be- 
cause the weather and other conditions always 
vary. Under the most favorable conditions of 
moisture and temperature it is probably never less 
than eight days from egg to adult fly and under 
unfavorable conditions it may be as long as six 
weeks. 

The larvae thrive best when the manure is kept 
quite wet. I have often found them in almost 
incredible numbers in stables that had not been 
cleaned for some time. The horses standing there 
at night added fresh material and kept it just wet 
enough to make conditions almost ideal (Fig. 49). 

The pupae are usually found where the manure 
is a little dryer, but it must not be too dry. When 
the flies issue from the pupae they push their way 
up to the surface where they remain for a short 
time and allow the body to harden and the wings 
to dry before they fly away to other manure or, 
as too often happens, to some near-by kitchen or 
restaurant or market place. 

Of course it is impossible for them to issue from 



House-Flies or Typhoid-Flies 65 

this filth without more or less of it clinging to their 
bodies. Now if these flies would breed only in 
barn-yard manure and fly directly from the stable 
to the house there would be comparatively little 
reason to complain, at least from a sanitary stand- 
point, for the amount of barn-yard filth that they 
carried to Our food would be of little consequence. 
But when they breed in privy vaults or similar 
places, or visit such places before coming into the 
house or dairy or market place the results may be 
much more serious. 

FLIES AND TYPHOID 

It has been abundantly demonstrated that the ex- 
crement or the urine of a typhoid patient may con- 
tain virulent germs for some time before he is aware 
that he has the disease, and it has been shown that 
the germs may be present for weeks or months, 
and in some cases even years after the patient has 
recovered. If a fly breeds in such infected ma- 
terial, or feeds or walks on it, it is very apt to get 
some of the germs on its body where they may re- 
tain their virulence for some time, and should it 
visit our food while covered with these germs some 
of them would probably be left there where they 
might produce serious results. More than that. If 
the fly should feed on such infected material the 



66 Insects and Disease 

typhoid germs would go on developing in the in- 
testine of the fly and would be passed out with the 
feces in which they retain their virulence for some 
days. In other words, the too familiar " fly-specks " 
are not only disgusting, but may be a very grave 
source of danger. It will be seen that in this way 
several members of a community might become 
infected with the typhoid germs before anyone was 
aware that there was a case of typhoid or a " bacil- 
lus carrier" in the neighborhood. 

One more example out of the scores that might 
be cited to show how the fly may carry typhoid 
germs. They may enter the sick chamber in the 
home or in the hospital and there gain access to the 
typhoid germs. These they may carry to other 
parts of the house or to near-by houses, or the flies 
may light on passing carriages or cars and be 
carried perhaps for miles before they enter another 
house and contaminate the food there. 

These are hypothetical cases, but they illustrate 
what is taking place hundreds of times every season 
all over the world wherever typhoid fever and flies 
occur, and no country or race is known to be im- 
mune from typhoid, and the fly is found "wherever 
man is found." 

In the summer of 1898 a commission was ap- 
pointed to investigate the prevalence of typhoid 



House-Flies or Typhoid-Flies 67 

fever in the United States Army Concentration 
Camps. The following are some of the conclusions 
as reported by Dr. Vaughan : 

"flies undoubtedly served as carriers of the 
infection 

"My reasons for believing that flies were active in 
the dissemination of typhoid may be stated as follows: 

"a. Flies swarmed over infected fecal matter in the 
pits and then visited and fed upon the food prepared 
for the soldiers at the mess tents. In some instances 
where lime had recently been sprinkled over the con- 
tents of the pits, flies with their feet whitened with 
lime were seen walking over the food. 

"b. Officers whose mess tents were protected by means 
of screens suffered proportionately less from typhoid 
fever than did those whose tents were not so protected. 

"c. Typhoid fever gradually disappeared in the fall 
of 1898, with the approach of cold weather, and the 
consequent disabling of the fly. 

"It is possible for the fly to carry the typhoid bacil- 
lus in two ways. In the first place, fecal matter con- 
taining the typhoid germ may adhere to the fly and be 
mechanically transported. In the second place, it is 
possible that the typhoid bacillus may be carried in the 
digestive organs of the fly and may be deposited with 
its excrement." 

In Dr. Daniel D. Jackson's report to the Mer- 
chants' Association of New York on the " Pollution 



68 Insects and Disease 

of New York Harbor as a Menace to the Health by 
the Dissemination of Intestinal Diseases Through 
the Agency of the Common House-fly," he shows 
graphically that the prevalence of typhoid and 
other intestinal diseases is coincident with the 
prevalence of flies, and that the greatest number 
of deaths from such diseases occurs near the river 
front where the open or poorly constructed sewers 
scatter the filth where the flies can feed on it, or 
along the wharves with their inadequate accom- 
modations and the resulting accumulation of 
filth. 

FLIES AND OTHER DISEASES 

Not only is the house-fly an important factor in 
the dissemination of typhoid fever, but it has been 
definitely shown that it is capable of transmitting 
several other serious diseases. 

The evidence that flies carry and spread the 
deadly germs of cholera is most conclusive. The 
germs may be carried on the body where they will 
live but a short time, or they may be carried in the 
alimentary canal where they will live for a much 
longer period and are finally deposited in the fly- 
specks where they retain their virulence for some 
time. Flies that had been allowed to contaminate 
themselves with cholera germs were allowed ac- 
cess to milk and meat. In both cases hundreds of 



House-Flies or Typhoid-Flies 69 

colonies of the germs could later be recovered from 
the food. As with the typhoid germs milk seems to 
be a particularly good medium for the develop- 
ment of the cholera germs. In several of the ex- 
periments that have been made along this line the 
milk has been readily infected by the flies visiting it. 

Of course an outbreak of cholera is of rare 
occurrence in our country, but unfortunately this 
is not so in regard to some other intestinal diseases 
such as diarrhea and enteritis which annually 
cause the death of many children, especially bottle- 
fed babies. Those who have made close studies of 
the way in which these diseases are disseminated 
are convinced that the flies are one of the most 
important factors in their spread. 

It has long been observed that flies are par- 
ticularly fond of sputum and will feed on it on the 
sidewalk, in the gutter, the cuspidor or wherever 
opportunity offers. It is well known, too, that 
the sputum of a consumptive contains myriads 
of virulent tubercular germs. A fly feeding and 
crawling over such material must necessarily get 
some of it on its body, and as it dries and the insect 
flies about the germs will be distributed through 
the air, possibly over our food. It has been shown 
that the excretion from a fly that has fed on tuber- 
cular sputum contains tubercular bacilli that may 



70 Insects and Disease 

remain virulent for at least fifteen days. Thus we 
see again the danger that may lurk in the too 
familiar " fly-specks." 

Although it is generally supposed that the flea is 
solely responsible for the spread of the bubonic 
plague and no doubt is the principal distributing 
agent, the fact must not be overlooked that the 
house-fly may also be of considerable importance 
in this connection. Carefully planned experiments 
have shown that flies that have become infected by 
being fed on plague-infected material may carry 
the germs for several days and that they may die 
of the disease. During plague epidemics flies may 
become infected by visiting the sores on human or 
rat victims or by feeding on dead rats or on the ex- 
creta of sick patients, and an infected fly is always a 
menace should it visit our food or open wounds or 
sores. Anthrax bacilli are carried about and 
deposited by flies showing the possibility of the 
disease being spread in this way. 

Some believe that leprosy, smallpox and many 
other diseases are carried by the house-fly, so it is 
little wonder that it is fast losing its standing as a 
household companion and that we are beginning to 
regard it not only as a nuisance but as a source of 
danger which should no longer be tolerated in any 
community. 



House-Flies or Typhoid-Flies 71 

Of course only a small per cent of the flies that 
visit our food in the dairies or market places or 
kitchens actually carry dangerous diseases, but they 
are all bred in filth and it is not possible without 
careful experiments or laboratory analysis to de- 
termine whether any of the germs among the mil- 
lions that are on their bodies are dangerous or not. 
The chances that they may be are too great. The 
only safe way is to banish them all or to see that 
all of our food is protected from them. 

FIGHTING FLIES 

Screens and sticky fly-paper have their places 
and give some little relief in a well-kept house. 
But of what use is it to protect your food after it 
has entered your home if in the stores, in the 
market place, in the dairy barn, or dairy wagon, 
in the grocers' and butchers' cart, it has been ex- 
posed to contamination by hundreds of flies that 
have visited it. 

The problem is a larger one than keeping the 
house free from flies; larger but not more difficult, 
for the remedy is simple, effective, practicable and 
inexpensive. Destroy their breeding-places and 
you will have no flies. As the flies breed prin- 
cipally in manure the first remedial measure is to 
see that all manure is removed from the barn-yard 



72 Insects and Disease 

at least once a week and spread over the fields 
to dry, for the flies cannot breed in the dry ma- 
nure. If it is not practicable to remove it this 
often the manure should be kept in a bin that is 
closed so tight that no flies can get into it to lay 
their eggs. Sometimes the manure may be treated 
with some substance such as kerosene, crude oil, 
chlorid of lime, tobacco water or mixture of two 
or more of these and thus rendered unsuitable for 
the flies to breed in, but in general practice none 
of them has been found very satisfactory for the 
treatment is either not thorough enough or is too 
expensive of time and material. 

Outdoor privies and cesspools must be carefully 
attended to. The latter can be easily covered so no 
flies can get in and if the filthy and in every way 
dangerous pit under the privy be filled and the 
dry-earth closet substituted one of the greatest 
sources of danger, especially in the country and in 
towns with inadequate sewerage facilities, will be 
done away with. After these things are done there 
remain only the garbage cans and the rubbish 
heaps to look after. 

Of course your neighbor must keep his place 
clean too, for his flies are just as apt to come into 
your house as his, so the problem becomes one for 
the whole community. 



House-Flies or Typhoid-Flies J3 

Almost all cities and many of the smaller towns 
have ordinances which if enforced would afford 
adequate protection from flies, but they are sel- 
dom if ever rigidly enforced and it yet remains 
for some enterprising town to be able to advertise 
itself as a "speckless town" as well as a " spotless 
town." 

AN EXPERT'S OPINION 

In a recent important bulletin issued by the 
Bureau of Entomology, Dr. L. O. Howard dis- 
cusses the economic importance of several of the 
insects that carry disease. I wish to quote two or 
three paragraphs from the pages in which he dis- 
cusses the house-fly or typhoid fly to show the 
opinion of this excellent authority in regard to this 
pest. 

"Even if the typhoid or house fly were a creature 
difficult to destroy, the general failure on the part of 
communities to make any efforts whatever to reduce 
its numbers could properly be termed criminal neg- 
lect; but since, as will be shown, it is comparatively 
an easy matter to do away with the plague of flies, this 
neglect becomes an evidence of ignorance or of a care- 
lessness in regard to disease-producing filth which to 
the informed mind constitutes a serious blot on civi- 
lized methods of life." 

On another page : 



74 Insects and Disease 

"We have thus shown that the typhoid or house fly 
is a general and common carrier of pathogenic bacteria. 
It may carry typhoid fever, Asiatic cholera, dysentery, 
cholera morbus, and other intestinal diseases; it may 
carry the bacilli of tuberculosis and certain eye diseases. 
It is the duty of every individual to guard so far as 
possible against the occurrence of flies upon his prem- 
ises. It is the duty of every community, through its 
board of health, to spend money in the warfare against 
this enemy of mankind. This duty is as pronounced 
as though the community were attacked by bands of 
ravenous wolves." 

Again : 

"A leading editorial in an afternoon paper of the 
city of Washington, of October 20, 1908, bears the 
heading, 'Typhoid a National Scourge,' arguing that 
it is to-day as great a scourge as tuberculosis. The 
editorial writer might equally well have used the head- 
ing i Typhoid a National Reproach,' or perhaps even 
'Typhoid a National Crime,' since it is an absolutely 
preventable disease. And as for the typhoid fly, that a 
creature born in indescribable filth and absolutely 
swarming with disease germs should practically be in- 
vited to multiply unchecked, even in great centers of 
population, is surely nothing less than criminal." 

The whole bulletin (No. 78, Bureau of Entomol- 
ogy) should be read and studied by all who are 
interested in this subject. 



House-Flies or Typhoid-Flies JS 

OTHER FLIES 

Occasionally other flies looking more or less like 
the house-fly are seen in houses. Some of these 
have the same type of sucking mouth-parts and 
have habits very similar to the house-fly, but as 
they are usually much less common and as nearly 
all that has been said in regard to the house-fly 
would apply equally well to them and as the same 
measures should be adopted in fighting them they 
need not be discussed further here. 

I have already called attention to the fact that 
a fly which looks very much like the house-fly is 
sometimes found in the house and will often bite 
severely. It has quite a different style of beak, one 
that is fitted for piercing so it may suck the blood 
of its victim (Fig. 51). As these flies often seem 
to be more persistent before a rain the weather 
prophet will tell you that "It is surely going to rain 
for the house-flies are beginning to bite." 

These stable-flies, as they are called, are great 
pests of cattle and horses in some sections. It is 
thought that they are important factors in the 
spread of some of the diseases of domestic animals, 
and their habit of sometimes attacking human be- 
ings makes it possible for them to carry certain 
disease germs from animals to man or from man 
to man. 




CHAPTER VI 

MOSQUITOES 

OSQUITOES are no more abundant now 
than they have been in the past, but 
when Linnaeus in 1758 made his list of 
all the animals known to exist at that 
time he catalogued only six species of mosquitoes. 
Only a few years ago, 1901, Dr. Theobald of the 
British Museum published a book on the mosqui- 
toes of the world in which he listed three hundred 
and forty-three kinds. Soon other volumes ap- 
peared, adding more species, and systematists 
everywhere have been describing new ones until 
now the total number of described species is prob- 
ably over five hundred, more than sixty of which 
occur in the United States. 

This shows only one phase of the great interest 
that has been taken in the mosquitoes since the 
discovery of their importance as carriers of disease. 
Not only have they been studied from a systematic 
standpoint but an endless amount of work has been 

done and is being done in studying their develop- 

76 




Fig. 51 




Fig. 52 

Fig. 50 — Pupa of house-fly with the end broken to allow 
the fly to issue. 

Fig. 51 — Head of stable-fly showing sharp piercing beak. 
Fig. 52 — Mass of mosquito eggs {Theobaldia incidens). 




Fig. 53 — Mosquito eggs and larva; (Theobaldia incidens); two 
larva: feeding on bottom, others at surface to breathe. 




'ig. 54 — Mosquito larvae (T. incidens), dorsal view. 



Mosquitoes 77 

ment, habits, and structure until now, if one could 
gather together all that has been written about 
mosquitoes in the last ten or twelve years he would 
have a considerable library. 

Those who are particularly interested in the 
group will find some of these books and papers 
easily accessible, so there may be given here only 
a brief summary of the more important facts in 
regard to the structure and habits of the mos- 
quitoes in order that we may more readily under- 
stand the part that they play in the transmission 
of diseases and see the reasonableness of the 
recommendations in regard to fighting them. 

THE EGGS 

Mosquito eggs are laid in water or in places 
where water is apt to accumulate, otherwise they 
will not hatch. Some species lay their eggs in lit- 
tle masses (Fig. 52) that float on the surface of 
the water, looking like small particles of soot. 
Others lay their eggs singly, some floating about 
on the surface, others sinking to the bottom 
where they remain until the young issue. Some 
of the eggs may remain over winter, but usually 
those laid in the summer hatch in thirty-six to 
forty-eight hours or longer according to the tem- 
perature. 



78 Insects and Disease 

THE LARVJE 

When the larvae are ready to issue they burst 
open the lower end of the eggs and the young wrig- 
glers escape into the water. The larvae are fitted 
for aquatic life only, so mosquitoes cannot breed 
in moist or damp places unless there is at least 
a small amount of standing water there. A very 
little will do, but there must be enough to cover 
the larvae or they perish. 

The head of the larvae of most species is wide 
and flattened. The eyes are situated at the sides, 
and just in front of them is a pair of short antennae 
which vary with the different species. 

The mouth-parts too vary greatly according to 
the feeding habits. Some mosquito larvae are 
predaceous, feeding on the young of other species 
or on other insects. These of course have their 
mouth-parts fitted for seizing and holding their 
prey. Most of the wrigglers, however, feed on 
algae, diatoms, Protozoa and other minute plant 
or animal forms which are swept into the mouth 
by curious little brush-like organs whose move- 
ments keep a stream of water flowing toward the 
mouth. 

Another group containing the Anopheles are 
intermediate between these two and have mouth- 
parts fitted for feeding on minute organisms as 




Fig. 55 — Eggs, larva; and pupae of mosquitoes (7\ incidens). 




Fig. 56 — Larva of mosquito (T. incidens). 




Fig. 57— Mosquito larvae and pupae (T. incidens) with their 
breathing-tubes at the surface of the water. 




FlG. 58 — Anopheles larva- (A. maculipennis) resting at the surface of 
the water. 



Mosquitoes 79 

well as for attacking and holding other larger 
things. 

A few kinds feed habitually some distance be- 
low the surface, others on the bottom, while still 
others feed always at the surface. With one or two 
exceptions, the larvae must all come to the surface to 
breathe (Figs. 53-57)- Most species have on the 
eighth abdominal segment a rather long breathing- 
tube the tip of which is thrust just above the surface 
of the water when they come up for air. In this 
tube are two large vessels or tracheae which open 
just below the tip of the tube and extend forward 
through the whole length of the body, giving off 
branches here and there that divide into still smaller 
branches until every part of the body is reached 
by some of the small divisions of this tracheal sys- 
tem that carries the oxygen to all the tissues. The 
length of the breathing-tube is correlated with the 
feeding-habits of the larvae. Anopheles larvae 
which feed at the surface have very short tubes 
(Fig. 58), others that feed just below the surface 
have breathing-tubes as long or very much longer 
than the ninth abdominal segment. The last seg- 
ment has at its tip four thin flat plates, the tra- 
cheal gills. These too are larger or smaller ac- 
cording to the habits of the larvae. Those species 
that feed close to the surface and have the tip of 



80 Insects and Disease 

the breathing-tube above the surface most of the 
time have very small tracheal gills, while those that 
feed mostly on the bottom have them well de- 
veloped. 

When first hatched the larvae are of course very 
small. If the weather is warm and the food is 
abundant they grow very rapidly. In a few days 
the outer skin becomes rather firm and inelastic so 
it will not allow further growth. Then a new skin 
forms underneath and the old skin is cast off. This 
process of casting off the old skin is called molting, 
and is repeated four times during the one, two, 
three or more weeks of larval life. 

PUPA 

With the fourth molt the active feeding larva 
changes to the still active but non-feeding pupa 
(Fig. 59). The head and thorax are closely united 
and a close inspection will reveal the head, antennae, 
wings and legs of the adult mosquito folded away 
beneath the pupal skin. Instead of the breathing- 
tube on the eighth segment of the abdomen as in 
the larva, the pupa has two trumpet-shaped tubes 
on the back of the thorax through which it now gets 
its air from above the surface. The pupal stage 
lasts from two to five or six days or more. When 
the adult is ready to issue the pupal skin splits 




Fig, 59— Mosquito pups (T. incidens) resting at the surface of 
the water. 




Fig. 60 — Mosquito pupa (T. incidens) with its breathing-tubes in 
an air bubble below the surface of the water. 




Fig.. 61 — Mosquito larvae and pupae (T. incidens) resting at the 
surface of the water. 




Fig. 62 — A female mosquito (T, incidens); note the thread-like 
antennae. 




Flo 6 ; A male mosquito (T. incidens); note the feathery antenrce 



Mosquitoes 81 

along the back and the mosquito gradually and 
slowly issues. It usually takes several minutes 
for the adult to issue and for its wings to become 
hard enough so it can fly. In the meantime, it is 
resting on the old pupal skin or on the surface of 
the water, where it is entirely at the mercy of any 
of its enemies that might happen along and is in 
constant danger of being tumbled over should the 
water not be perfectly smooth. 

THE ADULT 

The adult mosquito is altogether too familiar an 
object to need description, but it is necessary that 
we keep in mind certain particular points in re- 
gard to its structure, in order that we may better 
understand how it is that it is capable of trans- 
mitting disease. 

If we examine closely the antennae of a number 
of mosquitoes that are bothering us with their too 
constant attentions we shall see that they all look 
very much alike (Fig. 62), small cylindrical joints 
bearing whorls of short fine hairs. But if we 
examine a number of mosquitoes that have been 
bred from a jar or aquarium we will find two 
types of antennae, the one described above belong- 
ing to the female. The antennae of the male 
(Fig. 63) are much more conspicuous on account 



82 Insects and Disease 

of the whorl of dense, fine, long hairs on each 
segment. Another interesting difference in the 
antennae is to be noted in the size of the first joint. 
In both sexes it is short and cup-shaped, but in the 
male it is somewhat larger. This basal segment 
contains a highly complex auditory organ which 
responds to the vibrations of the whorls of hairs 
on the other segments. Interesting experiments 
have shown that these hairs vibrate best to the 
pitch corresponding to middle C on the piano, the 
same pitch in which the female "sings." Of 
course mosquitoes and other insects have no voice 
as we ordinarily understand the word, but produce 
sound by the rapid vibration of the wings or by the 
passage of air through the openings of the tracheae. 
The males and females are thus easily distin- 
guished and, as we shall see later, this is of some 
importance for only the females can bite. The 
males and females differ in another way. Just be- 
low the antennae and at the sides of the proboscis or 
beak is a pair of three- to five-jointed appendages, 
the maxillary palpi or mouth-feelers which in the 
females of most species are very short (Fig. 64) 
while in the males they are usually as long as 
the proboscis (Fig. 65). The females of Anopheles 
and related forms have palpi quite as long as the 
males, but they are slender throughout while the 




Fig. 64 — Head and thorax of female mosquito [Ochlerotatus lati- 
vittatus); the short maxillary palpi are just above the proboscis 
and below the thread-like antenna. 




Fig. 65 — Head and thorax of male mosquito (O. lativittatus); the 
maxillary palpi are as long as the proboscis. 



• 



Fig. 66 — Head of female mosquito (Anopheles), with mouth- 
parts separated to show the needle-like parts: a, a antenn-p; 
b, b, palpi; c, labrum; d, d, mandibles; e, hypopharynx; 
/./, maxillae; g, labium; h, labella. (After Manson.) 




Fig. 67 — Cross-section of proboscis of female (a) and male (b) 
mosquito. Ixe, labrum-epipharynx; mn, mandibles; mx, maxillae; 
hp, hyjopharynx; sal, salivary duct; li, labium; tr, trachea; mus, 
inuM les. (After Nuttall and Shipley.) 



Mosquitoes 83 

male palpi are usually somewhat enlarged toward 
the tip and bear more or less conspicuous patches 
of rather long hairs or scales. 

THE MOUTH-PARTS 

The mouth-parts of the mosquito are of course 
of particular interest to us. At first they appear to 
consist of a long slender beak or proboscis, but by 
dissecting and examining with a microscope we 
find this beak to be made up of several parts 
(Fig. 66). The labium, which is the largest and 
most conspicuous, is apparently cylindrical but is 
grooved above throughout its length. At the tip 
of the labium are the labellae, two little lobes which 
serve to guide the piercing organs. Lying in this 
groove along the upper side of the labium are six 
very fine, sharp-pointed needles. The uppermost 
of these, the labrum-epipharynx, or labrum as we 
will call it, is the largest and is really a hollow tube 
very slightly open on its under side. Just below 
this is the hypopharynx, the lateral margins of 
which are very thin. Down through the median 
line of the hypopharynx runs a minute duct 
(Fig. 67, sal) which, though exceedingly small, is of 
very great importance, for through it is poured the 
saliva which may carry the malaria germs into the 
wound made when the mosquito bites. The other 



84 Insects and Disease 

four needles consist of a pair of mandibles which 
are lance-shaped at the tip and a heavier pair 
of maxillae, the tips of which are serrate on one 
edge. 

HOW THE MOSQUITO BITES 

When the female mosquito is feeding on man or 
any other animal the tip of the labium is placed 
against the surface and the six needles are thrust 
into the skin, the labellse serving as guides. As 
they are thrust deeper and deeper the labium is 
bowed back to allow them to enter. As soon as the 
wound is made the insect pours out through the 
tube of the hypopharynx some of the secretion from 
the salivary glands and then begins to suck up 
the blood through the hollow labrum into the 
pharynx and on into the stomach. 

The mouth-parts of the male differ in some im- 
portant respects from those of the female. The 
hypopharynx is united to the labium, the mandi- 
bles are wanting and the maxillae are very much 
reduced so that the insect is unable to pierce the 
tough skin of animals. The male feeds on the 
juices of plants as do the females when they can- 
not get blood. It is not at all necessary for mos- 
quitoes to have the warm blood of man or other 
animals. Comparatively few of them ever taste 



Mosquitoes 85 

blood. They have been seen feeding on blossoms, 
ripe fruit, watermelons, plant juices, etc. They 
are very fond of ripe bananas and are fed on them 
in the laboratory when we wish to keep mosquitoes 
for experimental purposes. 

THE THORAX 

The middle part of the body, called the thorax, 
is really a strong box with heavy walls for the at- 
tachment of the powerful wing and leg muscles. 
The three pairs of legs are covered with hairs and 
scales, and their tips are provided with a pair of 
claws which vary somewhat in the different spe- 
cies. The wings (Fig. 68) are long and narrow 
with a characteristic venation. Along the veins 
and the margin of the wings are the scales which 
readily enable one to distinguish mosquitoes from 
other insects that may look much like them. In 
some species these scales are long and narrow, al- 
most hair-like, in others they are quite broad and 
flat (Fig. 69). Just back of the wings is a pair 
of balancers, short thread-like processes knobbed 
at the end. These probably represent the second 
pair of wings with which most insects are pro- 
vided, and seem to serve as balancers or orienting 
organs when the insect is flying. On the sides of 
the thorax are two small slit-like openings, the 



86 Insects and Disease 

breathing-pores. These are the openings into the 
tracheal or respiratory system. 

THE ABDOMEN 

The long cylindrical abdomen is composed of 
eight segments. These are rather strongly chiti- 
nized above and below, but a narrow strip along 
the side is unchitinized. In this strip are situated 
the abdominal breathing-pores. The tip of the 
abdomen is furnished with a pair of movable 
organs, which in the male are variously modified 
and serve as clasping organs at mating time. 

THE DIGESTIVE SYSTEM 

The mouth-parts of the mosquito have just been 
described. It will be remembered that the labrum 
is provided with a groove. Through this the blood 
or other food is sucked up by means of a strong- 
walled pumping organ, the pharynx, situated in 
the head (Fig. 70). Just back of the pharynx is the 
esophagus which leads to the beginning of the 
stomach. Close to its posterior end the esophagus 
gives off three food reservoirs, two above and a 
single larger one below. In dissections these will 
often be seen to be filled with minute bubbles. The 
stomach reaches from the middle of the thorax to 
beyond the middle of the abdomen. At its pos- 




Fig. 68 — Wing of Mosquito (O. lativittatus) . 




Fig. 69 — End of mosquito wing highly magnified to show the 
scales on the veins. 



Dorsal reservoir «. 

Oesophageal valve^. , . 
< 6 Malphigian tubes 




Sahvaryduct Ventral reserve i^J^* 

Proboscis Salivary glands 

Fig. 70 — Diagram to show the alimentary canal and salivary 
glands of a mosquito. 





FiG. 71 — Salivary glands of Culex at right. Anopheles at left. 

(After Christophers.) 



Mosquitoes 87 

terior end are given off five long slender processes, 
the Malpighian tubules which are organs of excre- 
tion, acting like the kidneys of higher animals. 
The hindgut is that portion of the intestine from 
the stomach to the end of the body. 

THE SALIVARY GLANDS 

Lying under the alimentary canal in the forward 
part of the thorax are the salivary glands. There 
are two sets of these, each having three lobes with 
a common duct which joins the duct from the other 
set a short distance before they enter the base of 
the hypopharynx. Each of these lobes is made up 
of a layer of secreting cells (Fig. 71) which pro- 
duces the saliva that is poured into the wound as 
soon as the insect pierces the skin of the victim, 
and we shall see, too, that the malarial germs also 
collect in these glands to be carried by the saliva 
to the new host. 

EFFECTS OF THE BITE 

After a mosquito has bitten a person and with- 
drawn the stylets, a small area about the puncture 
whitens, then soon becomes pink and begins to 
swell, then to itch and burn. Some people suffer 
much more from the bites of mosquitoes than do 
others. For some such bites mean little or no in- 



88 Insects and Disease 

convenience, indeed may pass wholly unnoticed, 
to others a single bite may mean much annoyance, 
and several bites may cause much suffering. 

After an hour or so the itching usually ceases, 
but in some cases it continues longer. In some in- 
stances little or no irritation is felt until some hours, 
sometimes as much as a day, after the bite. In 
such cases the effect of the bite is apt to be severe 
and to last for several days. Sometimes a more or 
less serious sore will follow a bite, probably due to 
infection of the wound by scratching. It is doubt- 
less the saliva that is poured into the wound that 
causes the irritation. It is frequently asserted that 
if the mosquito is allowed to drink its fill and with- 
draw its beak without being disturbed no evil 
results will follow. Those who hold this theory 
say that the saliva that is poured into the wound is 
all withdrawn again with the blood if the mosquito 
is allowed to feed long enough. There may be 
some truth in this, but for most of us a bite means 
a hurt anyway and few will be content to sit per- 
fectly still and watch the little pest gradually fill 
up on blood. 

It is not known just what the action of the saliva 
is, its composition or reaction on the tissues. It is 
generally supposed to prevent coagulation of the 
blood that is to be drawn through the narrow tube 



Mosquitoes 89 

of the labrum. Others think that its presence 
causes a greater flow of blood to the wound. But 
the sad part of it is, for us at least, that it hurts 
and may cause malaria and possibly other dis- 
eases. 

HOW MOSQUITOES BREATHE 

Mosquitoes and other insects do not have any 
nostrils nor do they breathe through any open- 
ings on the head. Along the sides of the thorax 
and abdomen is a series of very minute open- 
ings known as the spiracles. Through these the 
air passes into a system of air- tubes, the tracheae. 
There are two main trunks or divisions of the 
tracheae just inside the body-wall and a number of 
shorter connecting trunks. From these larger 
vessels arise a great number of smaller ones which 
branch and subdivide again and again until all 
the tissues are supplied by these minute little air- 
tubes that carry the oxygen to all parts of the body 
and carry off the waste carbon dioxid. These air- 
tubes are emptied and filled by the contractions 
of the walls of the abdomen. When the body-wall 
contracts the air is forced out of the thin-walled 
trachea through the spiracles; when the pressure 
is removed they are refilled by the fresh air rushing 
in. 



90 Insects and Disease 

THE BLOOD 

After a mosquito has been feeding on a man or 
some other animal it is often so distended that the 
blood shows rich and red through the thin sides of 
the walls of the abdomen. This, however, is the 
blood of the victim and not of the mosquito. The 
blood of insects is not red but pale yellowish or 
greenish. It is not confined in definite vessels, but 
fills all the space inside the body cavity that is 
not occupied by some of the tissues or organs. 
It bathes the walls of the alimentary canal and 
gathers there the nourishment which it carries to 
all parts of the body. It does not carry oxygen or 
collect the carbon dioxid as does the blood of 
higher animals. That work, as we have just seen, 
is done by the air-tubes. Above the alimentary 
canal, extending almost the whole length of the ab- 
domen and thorax, is a thin-walled pulsating ves- 
sel, the heart. This consists of a series of chambers 
each communicating with the one in front of it by 
an opening which is guarded by a valve. When 
one of these chambers contracts it forces the blood 
that is in it forward into the next chamber which, in 
its turn, sends it on. As the walls relax the valves 
at the sides are opened and the blood that is in the 
body-cavity rushes in to fill the empty chamber. 





Fig. 72 Fig. 73 

Fig. 72 — Heads of Culicinas mosquitoes; a, male; b, female. (After Manson.) 
Fig. 73 — Heads of Anophelinae mosquitoes; c, male; d, female. (After 

Manson.) 




Fig. 74 — Wing of A nopheles maculipennis. 




Fig. 75 — Wing of Theobaldia incidens. 





Fig. 76 



Fig. 77 




Fig. 78 FlG - 79 

FlG ? 6— A non-malarial mosquito (T. incidens), male, standing on the wall. 
Fig. 77 — Female of same. 

p IG 7 8— A malarial mosquito (A. maculipennis), male, standing on the wall. 
Fig. 79 — Female of same. 



Mosquitoes 91 

As these regular rythmical pulsations recur the 
blood is forced forward through the heart into the 
head where it bathes the organs there. We shall 
see in another chapter that the malarial parasite 
escapes from the walls of the stomach of the mos- 
quito into the blood in the body-cavity and finally 
reaches the salivary glands. As the heart is con- 
stantly driving blood to this part of the body the 
parasites readily reach the glands from which they 
finally escape into the new host. 

CLASSIFICATION 

For our purpose it will not be necessary to try to 
give a system of classification of all the mosquitoes. 
Those interested in this phase of the subject will 
find several books and papers devoted wholly to it. 
It is quite important, however, that we know 
something about a few of the more familiar groups 
and kinds, especially those concerned in the trans- 
mission of diseases. 

THE ANOPHELES 

In pointing out the differences between male and 
female mosquitoes we noted that in one group, the 
genus Anopheles, both sexes have long maxillary 
palpi (Figs. 72, 73). This is the most important 
character separating this genus from the other 



92 Insects and Disease 

common forms and as the Anopheles are the ma- 
laria carriers it is important that this difference be 
remembered. Most of the members of this group 
have spotted wings (Fig. 74), but as some other 
common kinds also have spotted wings (Fig. 75) 
this character will not always be reliable. When 
an Anopheles mosquito is at rest the head and pro- 
boscis are held in one line with the body and the 
body rests at a considerable angle to the surface 
on which it is standing. Other kinds rest with the 
body almost or quite parallel to the surface on 
which they are standing. So if you find a female 
mosquito with long mouth-palpi and spotted 
wings resting at an angle to the surface on which 
it stands you may be reasonably sure that it is an 
Anopheles and therefore may be dangerous (Figs. 

76, 77, 78, 79)- 

In the United States there are three species of 
Anopheles — maculipennis, punctipennis and cru- 
cians — which are common in various localities, 
and one or two other species that so far as known 
are local or rare. 

The Anopheles eggs are not laid in masses as are 
the eggs of many other mosquitoes, but are de- 
posited singly on the surface of the water where 
they may be found often floating close together. 

The eggs (Figs. 80, 81) are elliptical in outline 




Fig. 80 — Egg of Anopheles, side view. (After 
Nuttall and Shipley.) 




Fig. 8 i — Egg of Anopheles, dorsal view. (After 
Nuttall and Shipley.) 




Fig. 82 — Anopheles larvae, the one to the right feeding. 



Fig. 83 — Anopheles larvae, the one to the right feeding, the 
other just coming to the surface. 




Fig. 84 — Anopheles larva, dorsal view. 




Fig. 85 — Anopheles pupje resting at surface of water. 



Mosquitoes 93 

and are provided with a characteristic membranous 
expansion near the middle. 

The larvae may be found at the proper season 
and in the localities where they are abundant in 
almost any kind of standing water, in clear little 
pools beside running streams, in the overflow from 
springs, in swamps and marshy lands, in rain- 
barrels or any other places or vessels where the 
water is quiet. They do not breed in brackish 
water. As they feed largely on the algae or green 
scum on the surface of the water they are espe- 
cially apt to be found where this is present. We 
have already noted that their positions in the water 
differ from that assumed by other species (Fig. 82). 

As the breathing-tube is very short the larvae 
must come close to the surface to breathe, and 
when they are feeding we find them lying just un- 
der and parallel to the surface of the water with 
their curious round heads turned entirely upside 
down as they feed on the particles that are float- 
ing on the surface (Figs. 83, 84). 

The pupae do not differ very much from the 
pupae of other species although the breathing-tubes 
on the thorax are usually shorter and the creature 
usually rests with its abdomen closer to the sur- 
face, that is, it does not hang down from the surface 
quite as straight as do other forms (Fig. 85). 



94 Insects and Disease 

The adults may be found out of doors or in 
houses, barns or other outbuildings. They do not 
seem to like a draft and consequently will be more 
apt to frequent rooms or places where there is little 
circulation of air. Although they are usually sup- 
posed to fly and bite only in the evening or at night, 
they may occasionally bite in the daytime. One 
hungry female took two short meals from my arm 
while we were trying to get her to pose for a photo- 
graph one warm afternoon. 

The female passes the winter in the adult con- 
dition, hibernating in any convenient place about 
old trees or logs, in cracks or crevices in doors or 
out of doors. In the house they hide in the closets, 
behind the bureau, behind the head of the bed, or 
underneath it, or in any place where they are not 
apt to be disturbed. During a warm spell in the 
winter or if the room is kept warm they may come 
out for a meal almost any time. 

THE YELLOW FEVER MOSQUITO 

Ranking next in importance to Anopheles as a 
disseminator of disease and in fact solely responsi- 
ble for a more dreaded scourge, is the species of 
mosquito now known as Stegomyia calopus. While 
this species is usually restricted to tropical or semi- 
tropical regions it sometimes makes its appearance 



Mosquitoes 95 

in places farther north, especially in summer time, 
where it may thrive for a time. The adult mos- 
quito (Fig. 104) is black, conspicuously marked 
with white. The legs and abdomen are banded 
with white and on the thorax is a series of white 
lines which in well-preserved specimens distinctly 
resembles a lyre. These mosquitoes are essentially 
domestic insects, for they are very rarely found ex- 
cept in houses or in their immediate vicinity. Once 
they enter a room they will scarcely leave it except 
to lay their eggs in a near-by cistern, water-pot, or 
some other convenient place. 

Their habit of biting in the daytime has gained 
for them the name of "day mosquitoes" to distin- 
guish them from the night feeders. But they will 
bite at night as well as by day and many other 
species are not at all adverse to a daylight meal, if 
the opportunity offers, so this habit is not distinc- 
tive. The recognition of these facts has a distinct 
bearing in the methods adopted to prevent the 
spread of yellow fever. There are no striking char- 
acters or habits in the larval or pupal stages that 
would enable us to distinguish without careful ex- 
amination this species from other similar forms 
with which it might be associated. For some time 
it was claimed that this species would breed only in 
clean water, but it has been found that it is not 



96 Insects and Disease 

nearly so particular, some even claiming that it 
prefers foul water. I have seen them breeding in 
countless thousands in company with Stegomyia 
scutellaris and Culex Jatigans in the sewer drains in 
Tahiti in the streets of Papeete. As the larvae feed 
largely on bacteria one would expect to find them 
in exactly such places where the bacteria are of 
course abundant. 

The fact that they are able to live in any kind of 
water and in a very small amount of it well adapts 
them to their habits of living about dwellings. 

So far as known the members of these two 
genera are the only two that are concerned in the 
transmission of disease in the United States. In 
other countries other species are suspected or 
proven disseminators of certain diseases, but these 
will be discussed in connection with the particular 
diseases in later chapters. 

OTHER SPECIES 

The many other species of mosquitoes that we 
have may be conveniently divided as to their 
breeding-habits into the fresh-water and the 
brackish-water forms. Among the fresh- water 
kinds some are found principally associated with 
man and his dwelling places, others live in the 
woods or other places and so are far less trouble- 



Mosquitoes 97 

some. Most of these do not fly far. Several of the 
species that breed in brackish water are great 
travelers and may fly inland for several miles. 
Thus the towns situated from one to three or four 
miles inland from the lower reaches of San Fran- 
cisco Bay are often annoyed more by the mos- 
quitoes that breed only in the brackish water on 
the salt marshes than they are by any of the 
fresh-water forms (Figs. 86, 87). The worst mos- 
quito pest along the coast of the eastern United 
States and for some distance inland is a species 
that breeds in the salt marshes. 

NATURAL ENEMIES OF MOSQUITOES 

In combating noxious insects we learned long 
ago that often the most efficient, the easiest and 
cheapest way is to depend on their natural ene- 
mies to hold them in check. Under normal or 
rather natural conditions we find that they are 
usually kept within reasonable bounds by their 
natural enemies, but under the artificial conditions 
brought about by the settling and developing of any 
district great changes come about. It very often 
happens that these changes are favorable to the 
development of the noxious insects and unfavorable 
to the development of their enemies. 

A striking example and one to the point is af- 



gS Insects and Disease 

forded in the introduction of mosquitoes into 
Hawaii. Up to 1826 there were no mosquitoes on 
these islands. It is supposed that they were intro- 
duced about that time by some ships that were 
trading at the islands. Indeed it is claimed that 
the very ship is known that brought them over 
from Mexico. 

Once introduced they found conditions there 
very favorable to their development, plenty of 
standing water and few natural enemies to prey on 
them, so they increased very rapidly and gradually 
spread over all the islands of the group. This was 
the so-called night mosquito, Culex pipiens. Much 
later another species, Stegomyia calopus, just as 
annoying and much more dangerous was intro- 
duced and has also become very troublesome. We 
have a few species of top-minnows (Fig. 88) occur- 
ring in sluggish streams in the southern part of the 
United States that are important enemies of the 
mosquitoes of that region. A few years ago some 
of these were taken over to Hawaii and liberated 
in suitable places to see if they would not help solve 
the mosquito problem there. The fishes seem to be 
doing well. Already they are destroying many 
mosquito larvae, and there are indications that they 
are going to do an important work, but of course 
can be depended on only as an aid. 





N^ 


• 


— — .-, — . 


If 


m ••» • 


/ 


| 


1 \ 

\ 

\ ■ 

\ 
\ 



Fig. 85 — Salt-mirsh mosquito (Ochlerotatus lativittatus) ; 
male. 




Fig. 87 — Salt-marsh mosquito (O. lativittatus); female. 







^1 




» _ 




^jf! 














■* / '-vsB 




* ■ 







Fig. 88 — Top-minnow {Mollienisia laiipinna). (From 
Bull., 47 U. S. Fish Com.) 




Fig. 89 — Dragon-flics. (From Kellogg's Amer. Insects.) 



Mosquitoes 99 

On account of the various habits of both the 
larvae and adults it will never be possible for any 
natural enemy or group of natural enemies effect- 
ively to control the mosquitoes of any region, but 
as certain of them are important as helpers they 
deserve to be mentioned. 

ENEMIES OF THE ADULTS 

Birds devour a few mosquitoes, the night-flying 
forms being particularly serviceable, but the num- 
ber thus destroyed is probably so small as to be of 
little practical importance. 

The dragon-flies (Figs. 89, 90, 91) or mosquito 
hawks have long been known as great enemies 
of mosquitoes, and they certainly do destroy many 
of them as they are hawking about places where 
mosquitoes abound. Dr. J. B. Smith of New Jer- 
sey very much doubts their efficiency, but obser- 
vations made by other scientific men would seem 
to indicate that they often devour large numbers 
of mosquitoes during the course of the day and 
evening. 

Spiders and toads destroy a few mosquitoes each 
night. Certain external and internal parasites de- 
stroy a few more, but the sum total of all of these 
agencies is probably not very considerable, for 
while the adults may have several natural enemies 



ioo Insects and Disease 

they are not of sufficient importance to have any 
appreciable effect on the number of mosquitoes in 
a badly infested region. 

ENEMIES OF THE LARVAE AND PUP/E 

The larvae and pupae on the other hand have 
many important enemies. Indeed under favorable 
conditions these may keep small ponds or lakes 
quite free from the pests. The predaceous aquatic 
larvae of many insects feed freely on wrigglers. 
The larvae of the diving beetles which are known 
as water-tigers are particularly ferocious and will 
soon destroy all the wrigglers in ponds where they 
are present (Fig. 92). Dragon-fly larvae also feed 
freely on mosquito larvae. Whirligig beetles are 
said to be particularly destructive to Anopheles 
larvae and many other insects such as water- 
boatmen, back-swimmers, etc., feed on the larvae 
of various species. A few of these introduced into 
a breeding-jar with Anopheles larvae will soon de- 
stroy all of them, even the very young bugs attack- 
ing larvae much larger than themselves. 

It is interesting to note that the larvae of some 
mosquitoes are themselves predaceous and feed 
freely on the other wrigglers that may chance to be 
in the same locality. 

Various species of fish are, however, the most im- 




Fig. 90 — The young (nymph) of 
a dragon-fly. (From Keliogg's 
Amer. Insects.) 




Fig. 91 — The cast skin (exuvae) of a dragon-fly nymph. 




Fig. 92 — Diving-beetles and back-swimmers. (From Kellogg's Amer. 

Insects.) 



Mosquitoes 101 

portant enemies of the mosquitoes. Great schools 
of tide-water minnows (Fig. 93) are often carried 
over the low salt-marshes by the extreme high- 
tides and left in the hundreds of tide pools as the 
tide recedes. No mosquitoes can breed in a pool 
thus stocked with these fish. In the fresh- water 
streams and lakes there are several species of the 
top-minnows, sticklebacks (Fig. 94), etc., that feed 
voraciously on mosquito larvae and unless the grass 
or reeds prevent the fish from getting to all parts of 
the ponds or lakes very few mosquitoes can breed 
in places where they are present. 

Minute red mites such as attack the house-flies 
and other insects sometimes attack adult mosqui- 
toes, but they are rarely very abundant. Parasitic 
roundworms attack certain species. Others suffer 
more or less from the attacks of various Sporozoan 
parasites. 

FIGHTING MOSQUITOES 

When mosquitoes are bothering us we usually 
begin by trying to kill the individual pests that are 
nearest to us. We try to crush them if they bite us; 
we screen the doors and windows to keep them 
from the house. In warmer countries the people 
are a little more hospitable and do not screen the 
mosquitoes out of the house entirely, but screen the 
beds for protection at night, and if the mosquitoes 



102 Insects and Disease 

get too insistent during the day the bed makes a 
safe and comfortable retreat. All the mosquitoes in 
a room may be killed by fumigating with sulphur at 
the rate of two pounds to the thousand cubic feet of 
air-space. Pyrethrum is also used largely, but it 
only stupefies the mosquitoes temporarily instead of 
killing them. While in that condition they may be 
swept up and destroyed. 

Various substances are sometimes used as re- 
pellants by those who must be in regions where the 
mosquitoes are abundant. With many of these, 
however, "the cure is worse than the disease. " 
Smudges are often built to the windward of a house 
or barn-yard and the smoke from a good smoldering 
fire will keep a considerable area quite free from 
mosquitoes. The man who can keep himself en- 
veloped in a cloud of tobacco smoke will not be 
bothered by mosquitoes. Oil of pennyroyal, oil of 
tar or a mixture of these with olive oil, and various 
other concoctions are sometimes smeared over the 
face and hands. These will furnish protection as 
long as they last. Dr. Smith says that he has 
found oil of citronella quite effective and of course 
less objectionable than the other things usually 
used. Care should be taken not to get it in the 
eyes. An ointment made of cedar oil, one ounce; 
oil of citronella, two ounces; spirits of camphor, 




Fig. 93 — Killifish (Fundulus heteroliatus). (From Bull. 47, U. S. Fish Com.) 





/ / 


^%K 






0$)- 


\ 


"v<N> 


■■'"> 

8s7 


: : - ' - ■'■.: 



Fig. 94 — Stickleback (Apeltes quadracus). (From Bull. 47, U. S. Fish Com.) 



Mosquitoes 103 

two ounces, is said to make a good repellant and is 
effective for a long time. 

FIGHTING THE LARV^ 

All of the efforts directed against the adult mos- 
quitoes are usually of little avail in decreasing the 
number in any region. It is comparatively easy, 
however, to fight them successfully in the larval 
stage. We have seen that standing water is abso- 
lutely necessary for mosquitoes to breed in. This 
makes the problem much simpler than if they 
could breed in any moist places such as well- 
sprinkled lawns, a shady part of the garden, etc. 
The whole problem of successful campaigns 
against the mosquitoes resolves itself into the prob- 
lem of rinding and destroying or properly treat- 
ing their breeding-places. We have seen how cer- 
tain kinds, such as the yellow fever mosquito, are 
" domestic " species. They never go far from 
their breeding-places. If a house is infected by one 
of these species the immediate premises should be 
searched for the source. Cisterns, rain-barrels, 
sewer-traps, cesspools, tubs or buckets of water or 
old tin cans in out-of-the-way corners, are all suit- 
able places for them to breed in. Cisterns and rain- 
barrels should be thoroughly screened so that no 
mosquitoes can get in or out, or the surface should 



104 Insects and Disease 

be covered with a film of kerosene which will kill all 
the larvae in the water when they come to the sur- 
face to breathe, and will also kill the females when 
they come to deposit their eggs. The vent to open 
cesspools should be thoroughly screened or the 
surface of the water kept well covered with oil. 
Water standing in any vessels in the yards should 
be emptied every week or ten days and the old tin 
cans destroyed or hauled away. In fighting these 
domestic species you need be concerned only with 
your own yard and that of your near-by neighbors. 
Other species, while also rather local in their dis- 
tribution, fly much farther than the really domestic 
ones. In fighting these the region for a consid- 
erable distance around must be taken into consid- 
eration. Watering- troughs (Fig. 95) that are left 
filled from week to week, the overflow from such 
places, and the tracks made in the mud round 
about them (Fig. 96), small sluggish streams, irri- 
gating ditches, and small ponds or lakes not sup- 
plied with fish are excellent breeding-places for sev- 
eral species of mosquitoes including Anopheles and 
others. The remedy at once suggests itself. The 
watering-trough can be emptied and renewed every 
week during the summer time, the overflow can be 
taken care of in a ditch that will lead it away from 
the trough to where it will sink into the ground, the 



Mosquitoes 105 

banks of the streams or ponds or lakes can be 
cleared in such a way that fish can get to all parts of 
the water ; most of the small ponds can be drained or 
their surface may be covered over with a thin film of 
kerosene. This is best applied as a spray; one 
ounce to fifteen square feet will suffice. If the oil is 
simply poured over the surface more will be required. 

The fighting of the species that breed on the ex- 
tensive salt-marshes in many regions is a larger 
and more difficult problem, but as it is a matter 
that usually concerns large communities, sometimes 
whole states, it can be dealt with on a larger scale. 
The very excellent results that have been accom- 
plished in New Jersey and on the San Francisco 
peninsula, and in a smaller way in other places, 
show what may be done if the community goes 
about the fight in an intelligent manner. In the 
fight in New Jersey hundreds of acres of tide-lands 
have been drained so that they no longer have tide 
pools standing where the mosquitoes may breed. 
When it is impracticable to drain them the pools 
may be sprayed occasionally with kerosene. 

The value of the land that is reclaimed by a good 
system of draining is often enough to pay many 
times over the cost of draining, thus the mosquitoes 
are gotten rid of and the land enhanced in value by 
a single operation. 




CHAPTER VII 

MOSQUITOES AND MALARIA 

|VER since the beginning of history we 
have records of certain fevers that have 
been called by different names accord- 
ing to the people that were affected. 
As we study these names and the various writings 
concerning the fevers we find that a great group 
of the most important of them are what we to-day 
know as malarial fevers. Not only are these ills 
as old as history but they have been observed over 
almost the entire inhabited earth. There are cer- 
tain regions in all countries where malaria does 
not occur, but almost always it will be found that 
other regions near by are infected and it very often 
happens that these infected regions are the most 
profitable parts of the land, the places where water 
is plentiful and vegetation is luxuriant. Indeed 
the coincidence of these two things, low-lying lands 
with an abundance of water, particularly stand- 
ing water, and malaria has always been noted and 
gave rise to the earliest theories in regard to the 

cause of the disease. 

1 06 



Mosquitoes and Malaria 107 

For instance, we find some of the very early 
writers emphasizing the point that swampy locali- 
ties should be avoided for they produce animals 
that give rise to disease, or that the air is poisoned 
by the breath of the swamp-inhabiting animals. 

These views of the origin of the fever prevailed 
until about the beginning of the eighteenth century 
when the recently discovered microscope began to 
reveal the various kinds of animalculae to be found 
in decaying material. 

In 1 7 18 Lancisi held that the myriads of insects, 
particularly gnats or mosquitoes, that arose from 
such swampy regions might carry some of these 
poisonous substances and by means of their pro- 
boscis introduce them into the bodies of the people, 
and although he had made no experiments to test 
the assumption he did not consider it impossible 
that such insects might also introduce the smallest 
animalculae into the blood. It took almost two 
centuries of study and investigation before this 
guess was proved to be right. 

One reason why the mosquitoes were not earlier 
associated with these diseases was that all who in- 
vestigated the matter at all turned their attention 
to the bad condition of the air in these swampy 
regions. Malaria means bad air. We all know 
that we can see the mists arising from such regions, 



108 Insects and Disease 

particularly in the evening or at night, and as ex- 
posure to these mists very often meant an attack 
of malaria they were naturally supposed to be the 
cause of the disease. So for a long time the whole 
attention of investigators was turned toward study- 
ing and analyzing these vapors, and various experi- 
ments were made which seemed to show conclu- 
sively that the malaria was caused only by these 
emanations. The investigations even went so far 
that the exact germs that were supposed to cause 
the fever were separated and experimented with. 

THE PARASITE THAT CAUSES MALARIA 

The blood had been studied time and again and 
the characteristic appearance of the blood of a 
malarial patient was well known. In 1880 Lave- 
ran, a French army surgeon in Algiers, began to 
study the blood of such patients microscopically 
and soon was able to demonstrate the parasite 
that caused the disease. His discoveries were not 
readily accepted, but other investigations soon con- 
firmed his observations and the fact was gradually 
firmly established. Not until recently, however, 
did this distinguished physician receive a full rec- 
ognition of his work. A few years ago he was 
awarded the Nobel prize for medicine, perhaps the 
highest honor that can be bestowed on any physician. 




Fig. 96 — Horse and cattle tracks in mud filled with water; good 
breeding-places for Anopheles. 




Fig. 97 — A malarial mosquito {Anopheles maculipennis); male. 




Fig. 98 — A malarial mosquito (A. maculipennis); female. 



Mosquitoes and Malaria 109 

It is interesting, too, to note in this connection that it 
was another French surgeon who in 1840 discovered 
that sulphate of quinine is a specific for malaria. 

The next important step was made in 1885 by 
Golgi, an Italian, who studied the life-history of the 
parasite in the blood and distinguished the three 
forms which cause the three most familiar kinds 
of malarial fevers, the tertian, the quartan and the 
remittent types. From this time on this parasite 
has been studied by physicians of many nationali- 
ties and the whole course of its life-history worked 
out. In order that we may understand how it was 
that mosquitoes were determined to be the means 
of disseminating this parasite we will discuss first 
its life-history in the human blood. 

The parasites that cause the malarial fevers are 
Sporozoans and belong to the genus Plasmodium. 
Other names such as Hamamceba and Laverania 
have been used for them, but the term Plasmodium 
is the one now most commonly employed. The 
three most common species are vivax, malarice 
and falciparum, causing respectively the tertian, 
quartan and remittent fevers. 

LIFE-HISTORY OF PARASITE 

The life-history of all of these is very similar, the 
principal difference being in the length of time it 



no Insects and Disease 

takes them to sporulate. Let us begin with the 
parasite after it has been introduced into the blood 
and trace its development there. At first it is slen- 
der and rod -like in shape. It has some power of 
movement in the blood-plasm. Very soon it at- 
tacks one of the red blood-corpuscles and gradually 
pierces its way through the wall and into the cor- 
puscle substance (Fig. 99); here it becomes more 
amoeboid and continues to move about, feeding all 
the time on the corpuscle substance, gradually de- 
stroying the whole cell. As the parasite feeds and 
grows there is deposited within its body a blackish 
or brownish pigment known as melanin. 

During the time that the parasite is feeding and 
growing it is also giving off waste products, as all 
living forms do in the process of metabolism, but as 
the parasite is completely inclosed in the corpuscle 
wall these waste products cannot escape until the 
wall bursts open. After about forty hours if the 
parasite is vivax or about sixty-five hours if it is 
malaria it becomes immobile, the nucleus divides 
again and again and the protoplasm collects around 
these nuclei, forming a number of small cells or 
spores, as they are called. In about forty-eight or 
seventy-two hours, depending on whether the para- 
site is vivax or malarice the wall of the corpuscle 
bursts and all these spores with the black pigment 



1 




Development of 
Parasite in 
) Q%Q _ Human Blbod. 



Some may be taken 
into the stomach 
of the Mosquito when 
it bites 



InSalivary Development 
Gland 7 
of (Tlosq. 

in the 

iTIosquito 





f'Kf. sw** 




Fig. 99 — Diagram to i.lustrate the life-history of the malarial para- 
site, i is a red blood-corpuscle, 2 to 7 shows the development of the 
parasite in the corpuscle, abed and a' b' c' and e the development of 
the parasite in the stomach of the mosquito, / g h i the development 
in the capsule on the outer wall of the stomach of the mosquito, k in 
the salivary gland. 




Fig. ico — Malarial mosquito (.4. maculipennis) on the 
wall. 




Fig. ioi — Malarial mosquito (A. maculipennis) standing on a table. 



Mosquitoes and Malaria in 

and the waste products that have been stored away 
within the cell are liberated into the blood-plasm. 

These spores are round or somewhat amoeboid 
and are carried in the blood for a short time. Very- 
soon, however, each one attacks a new red cor- 
puscle and the process of feeding, growth anc 
spore-formation continues, taking exactly the same 
time for development as in the first generation, s( 
every forty-eight hours in the case of the vivax, an< 
every seventy-two hours in the case of the malarice 
a new lot of these spores and the accompanying 
waste products are thrown out into the blood. 
Thus in a very short time many generations of 
this parasite occur and thousands or hundreds of 
thousands of the red-blood corpuscles are destroyed, 
leaving the patient weak and anemic. It will be 
seen, too, that the recurrence of the chills and fevers 
is simultaneous with the escaping of the parasites 
from the blood -corpuscles, together with the waste 
products of their metabolism. 

These waste products are poisonous, and it is be- 
lieved that this great amount of poison poured into 
the blood at one time causes the regular recurring 
crisis. Zoologists well know that this process of 
asexual reproduction, i. e., reproduction without 
any conjugation of two different cells, cannot go on 
indefinitely, and those who were studying the life- 



ii2 Insects and Disease 

cycle of these parasites were at a loss to know 
where the sexual stage took place. In the mean- 
time studies of other parasites more or less closely 
related to Plasmodium showed that the sexual stage 
occurred outside the vertebrate host. The remark- 
able work of Dr. Smith on the life-history of the 
germ that causes the Texas fever of cattle had 
a strong influence in directing the search for this 
other stage of the malarial parasite. Another thing 
that indicated that this sexual generation must 
take place outside the body of the vertebrate host 
was the fact that the investigators found that the 
parasites in certain of the cells did not sporulate 
as did the others. When these individuals were 
drawn from the circulation and placed on a slide 
for study it was found that they would swell up and 
free themselves from the inclosing corpuscle and 
some of them would emit long filaments which 
would dart away among the corpuscles. 

Many men have worked on this problem, but 
perhaps the most credit for its solution will always 
be given to Sir Patrick Manson, the foremost au- 
thority on tropical diseases, and to Ronald Ross, a 
surgeon in the English army. There is no more 
interesting and inspiring reading than that which 
deals with the development of the hypothesis by 
Manson and the persistent faith of Ross in the 



Mosquitoes and Malaria 113 

correctness of this theory, and his continuous in- 
defatigable labors in trying to demonstrate it. It 
was an important piece of scientific work, and 
shows what a man can do even when the obstacles 
seem insurmountable. 

THE PARASITE IN THE MOSQUITO 

Briefly stated again, the problem was this: We 
have here a parasite in the blood which behaves as 
do many other forms of life. Some of these para- 
sites do not go on with their development until 
they are removed from the circulation. Now, how 
are they thus removed from the circulation under 
normal conditions ? This must first be solved be- 
fore the still greater and more important problem 
of how the parasite gets from one human host to 
another can be taken up. In studying this over 
Manson reasoned that certain suctorial insects were 
the agencies through which blood was most com- 
monly removed from the circulation and he ven- 
tured the guess that this change in the parasite 
that may be seen taking place on the slide under 
the microscope, normally takes place in the stom- 
ach of some insect that sucks man's blood. Ross 
was greatly impressed with the theory and began 
his long and apparently hopeless task of finding 
these parasites in the stomach of some insect. 



ii4 Insects and Disease 

When we remember that they are so minute that 
they can only be seen by the use of the highest 
power of the microscope we can realize something 
of the magnitude of the task. Ross, who was at 
that time stationed in India, selected the mosquito 
as the most likely of the insects to be the host that 
he was looking for. For over two and one-half 
years he worked with entirely negative results, for 
after examining thoroughly many thousands of 
mosquitoes he found no trace of the parasite. 

Practically all his work was done on the most 
common mosquito of the region, a species of Culex. 
But one day a friend sent him a different mosquito, 
one with spotted wings, and in examining it he 
was interested to note certain oval or round nodules 
on the outer walls of the stomach. On closer ex- 
aminations he found that each of these nodules con- 
tained a few granules of the coal-black melanin of 
malarial fever. Further studies and experiments 
showed that these particular cells could always be 
found in the walls of the stomach of this particular 
species of mosquito a few days after it had bitten 
a malarial patient. This epoch-making discovery 
was made in 1898. Ross was detailed by the Eng- 
lish government to devote his whole time to the 
further solution of the problem, and after two 
years more of careful experimentation and study 



Mosquitoes and Malaria 115 

was able to give a complete life-history of this 
parasite. His experiments have been repeated 
many times, and the conclusions he arrived at are 
as undeniable as any of the known facts of science. 
The whole life-history as we now know it can 
be summed up as follows: The parasites develop 
within the circulation but certain of them seem to 
wander about and do not go on with their devel- 
opment there. When these particular parasites are 
taken into the stomach of most mosquitoes they 
are digested with the rest of the blood. But when 
they are taken into the stomach of a mosquito 
belonging to the genus Anopheles or other closely 
related genera they are not digested but go on with 
their development, conjugation and fertilization 
taking place, resulting in a more elongated form 
which makes its way through the walls of the stom- 
ach on the outside of which are formed the little 
nodules discovered by Ross on his mosquitoes. 
Within these nodules further division and develop- 
ment takes place until finally the nodule is burst 
open and many thousand minute rod-like organ- 
isms, sporozoites, are turned loose into the body- 
cavity of the mosquito. Owing to some unknown 
cause these little organisms are gathered together 
in the large vacuolated cells of the salivary glands 
of the mosquito, and when the mosquito bites a 



n6 Insects and Disease 

man or any other animal they pour down through 
the ducts with the secretion and are thus again in- 
troduced in the circulation. 

The nodules or cysts on the walls of the stom- 
ach of the mosquito may contain as many as ten 
thousand sporozoites, and as many as five hundred 
cysts may occur on a single stomach. 

It takes ten, twelve or more days from the time 
the parasites are taken into the stomach of the 
mosquito before they can go through their trans- 
formations and reach the salivary gland, the time 
depending on the temperature. So it is ten or 
twelve days or sometimes as much as eighteen or 
twenty days from the time an Anopheles bites a ma- 
larial patient before it is dangerous or can spread 
the disease. On the other hand, the sporozoites 
may lie in the salivary gland alive and virulent for 
several weeks. It does not give up all the para- 
sites at one time, so that three or four or more 
people may be affected by a single mosquito. 

It is well known that two parasites may often 
be seen in the same corpuscle. This is often simply 
a case of multiple infection, but Dr. Craig has very 
recently shown that under certain conditions two 
individuals may enter the same corpuscle and con- 
jugate and the resulting individual will be resistant 
to quinine and may remain latent in the spleen or 



Mosquitoes and Malaria 117 

bone marrow for a long time. Under favorable 
conditions it may again begin the process of mul- 
tiplication and the patient will suffer a relapse. 

SUMMARY 

Now let us sum up some of the reasons why we 
believe that the malaria fever can be transmitted 
only through the agency of mosquitoes. First, 
we know the life-history of the parasite, it has 
been studied in both of its hosts. Attempts have 
been made to rear it in other hosts but without 
avail, and we know from the general relations of 
the parasite that it must have this sexual as well 
as the asexual generations. Second, in some re- 
gions which would seem to be malarial, that is, 
where the miasmatic mists arise, no malaria occurs. 
Why ? Usually it can be definitely shown that no 
Anopheles occur there. Other mosquitoes may be 
there in abundance, but if no Anopheles, there is 
no malaria. In certain regions this is well demon- 
strated. The west coast of Africa is one of the 
worst pest-holes of malaria and Anopheles. The 
east coast has no malaria and no Anopheles. In 
many islands the same condition exists. On the 
other hand, the Fiji Islands have Anopheles but 
no malaria. No malaria has ever been introduced 
there to infect the mosquitoes. In the same way 



n8 Insects and Disease 

Stegomyia occurs in some of the South Sea islands 
and yet there is no yellow fever there. 

EXPERIMENTS 

We may review, too, a few of the classic experi- 
ments that have served to show that malaria can be 
contracted in no other way than through the bite 
of the mosquito. 

For many years Grassi, an Italian, devoted al- 
most his whole time to the study of malaria. In 
1900 he received permission from the government 
to experiment on the employees of a piece of rail- 
road that was being built through a malarial 
region. This was divided for the purpose of the 
experiment into three sections, a protected zone 
in the middle and an unprotected zone at each end. 

Those working in the protected zone had their 
houses completely screened and no one was al- 
lowed out of doors after sunset except they were 
protected with veils and gloves. Early in the 
season they were all given doses of quinine to pre- 
vent auto-infection. In the unprotected zone no 
screens were used and every one was allowed to 
go without special protection. The result for the 
summer was that there were no new cases of fever 
in the protected zone. In the unprotected zones 
practically all had the fever as usual. 




Fig. 102 — Salt-marsh mosquito (O. lativittatus) standing on a table. 




Fig. 103 — Anopheles hanging from the ceiling. 



Mosquitoes and Malaria 119 

In the same year two English physicians, Sam- 
bon and Low, went to Italy where they built a 
cabin in one of the marshes noted as being a 
malaria pest-hole. The house was thoroughly 
screened so that no mosquitoes could enter, but the 
windows were always open so as to admit the air 
freely day and night. Here they lived for three 
months, out of doors as much as they pleased dur- 
ing the day but inside where they were protected 
from the mosquitoes at night. No quinine was 
used and no fever developed, although all about 
them other people were having the fever as usual. 

Another English physician who had not been 
in malarial regions allowed himself to be bitten by 
infected mosquitoes sent from a malarial locality. 
In due time he developed the fever. Many other 
experiments made in various places might be cited. 
The results have all been practically the same. To- 
day the soldiers of many civilized nations are re- 
quired to protect themselves from mosquitoes be- 
cause it has been found that it pays. Disease has 
always been a worse terror than bullets in any war, 
and we are fast learning that the great loss from 
diseases heretofore considered unavoidable may be 
very largely eliminated by proper sanitary arrange- 
ments and protection from noxious insects. 




CHAPTER VIII 

MOSQUITOES AND YELLOW FEVER 

ELLOW fever is a disease, principally 
of seaport towns, from which the United 
States has suffered more than any other 
country. It is endemic only in tropical 
regions but is often carried to subtropical, some- 
times even to temperate zones where, if the proper 
mosquitoes exist, it may rage until frost. 

Vera Cruz, Havana, Rio de Janiero, and the 
west coast of Africa were long regarded as per- 
manent endemic foci, the disease appearing there 
in epidemic form from time to time, often spread- 
ing to other ports in more or less close communi- 
cation with such places. In the United States the 
Gulf states have been the greatest sufferers from 
the disease, although it has spread as far as Balti- 
more, Philadelphia and Washington, where at rare 
intervals it was most serious, abating its ravages 
only when frost came. 

The last severe outbreak occurred in New Or- 
leans in 1905 when eight thousand cases and nine 



Mosquitoes and Yellow Fever 121 

hundred deaths occurred. At that time there was 
waged one of the most remarkable warfares against 
death in its most terrifying form that the world 
has ever known. And, thanks to the achievements 
of science, particularly to the investigations of 
three men, one of whom gave his life to the cause, 
the fight was successful and this dreadful outbreak 
was checked just at the time when according to all 
precedent it should have been at its height. 

This result which at other times and under other 
conditions would have been considered miraculous 
was achieved not by the usual custom of isolation, 
quarantine, etc., but by a direct, we may almost 
say hand to hand, conflict with mosquitoes: the 
mosquitoes belonging to a particular genus and 
species, Stegomyia calopus (jasciata). 

Before taking up a discussion of this achieve- 
ment in New Orleans let us consider first the work 
of the men that made such results possible. 

For many years the cause and methods of dis- 
semination of this disease had been a puzzle to 
physicians and scientists. Very early it was be- 
lieved that it might be transmitted through the 
air, and the fact that infection usually occurred in 
the vicinity of the water and in the tropics or in 
midsummer led to the belief that the disease was 
due to fermentation. This theory received strong 



122 Insects and Disease 

support in the fact that serious outbreaks of the 
fever often followed the coming into port of vessels 
from the tropics with the water in their holds in an 
offensive condition. When it was discovered that 
bacteria were the cause of fermentation and also of 
many diseases this theory was considered abun- 
dantly proven. From time to time, announcements 
have been made that the particular species of bac- 
teria that causes the disease has been isolated, but 
there has always been something lacking in the 
final proof. 

Yellow fever has always been regarded as a very 
highly contagious as well as infectious disease, and 
the utmost precaution has been taken to isolate the 
patients when possible and in recent years strict 
quarantines have been established against infected 
localities and no person or commerce or even the 
mails were allowed to come from such places with- 
out thorough fumigations. But all these things 
proved unsatisfactory. The disease could not or- 
dinarily be checked by simply isolating the patients. 
Many people became sick without ever having been 
near a yellow fever patient, while others worked in 
direct daily contact with the disease and did not 
suffer from it. Those who had once had it and re- 
covered became practically immune, rarely suffer- 
ing from a second attack. Negroes may suffer 




Fig. 104 — Yellow-fever mosquito {Stegomyia caiopus). 
(R. Newstead, del.) 



Mosquitoes and Yellow Fever 123 

from the disease, but are usually regarded as prac- 
tically immune. 

It was early observed, too, that the danger zone 
might be quite well defined and that outside this 
zone one would be safe. More than a century 
ago the British troops and other inhabitants of Ja- 
maica found that by retreating to the mountains 
during the warm weather the non-immunes could 
escape the fever. It was also observed that those 
who slept on the first floor were more apt to take 
the disease than those on the second floor. 

THE YELLOW FEVER COMMISSION 

In 1900, during the American occupation of 
Cuba, yellow fever became very prevalent there. 
A board of medical officers was ordered to meet in 
Havana for the purpose of studying the disease 
under the favorable opportunities thus afforded. 
This board, which came to be known as the Yellow 
Fever Commission, was composed of Drs. Walter 
Reed, James Carroll, Jessie W. Lazear and Aristi- 
des Agramonte of the United States Army. Agra- 
monte was a Cuban and an immune, the others 
were non-immunes. Dr. Manson in his lectures on 
Tropical Medicines says of them: 

"I cannot pass on, however, to what I have to say 
in connection with this work without a word of admira- 



124 Insects and Disease 

tion for the insight, the energy, the skill, the courage, 
and withal the modesty and simplicity of the leader 
of that remarkable band of workers. If any man de- 
served a monument to his memory, it was Reed. If 
any band of men deserve recognition at the hands of 
their countrymen, it is Reed's colleagues. " 

Their first work was to determine whether any 
of the germs that had been claimed to be the 
cause of yellow fever were really responsible for 
the disease. Bacillus icteroides that for some time 
and by some investigators had been named as the 
offender was particularly investigated, but was 
proved to be a secondary invader only. 

Dr. Charles Finlay of Havana had been claiming 
for some years that the yellow fever was trans- 
mitted by means of the mosquito and possibly by 
other insects also. He even claimed to have proved 
this theory experimentally. We know now, how- 
ever, that there must have been errors in his ex- 
periments and that his patients became infected 
from sources other than those he was dealing with. 

The Yellow Fever Commission decided to put 
this theory to the test and secured a number of 
volunteers for the experiments. The first thing 
was to let an infected mosquito bite some non- 
immune person. How this was done and the re- 
sults, may be told in Dr. Carroll's own words. 



Mosquitoes and Yellow Fever 125 

EXPERIMENTS 

"Two separate lines of work now presented: one, 
the study of the bacterial flora of the intestine and 
anaerobic cultures from the blood and various organs; 
the other, the theory of the transmission of the disease 
by the mosquito, which had been advanced by Dr. Car- 
los Finlay in 1881. After due consideration it was de- 
cided to investigate the latter first. Then arose the 
question of the tremendous responsibility involved in 
the use of human beings for experimental purposes. 
It was concluded that the results themselves, if positive, 
would be sufficient justification of the undertaking. It 
was suggested that we subject ourselves to the same 
risk and this suggestion was accepted by Dr. Reed and 
Dr. Lazear. It became necessary for Dr. Reed to re- 
turn to the United States and the work was begun 
by Dr. Lazear, who applied infected mosquitoes to a 
number of persons, himself included, without result. 
On the afternoon of July 27, 1900, I submitted myself 
to the bite of an infected mosquito applied by Dr. La- 
zear. The insect had been reared and hatched in the 
laboratory, had been caused to feed upon four cases 
of yellow fever, two of them severe, and two mild. The 
first patient, a severe case, was bitten twelve days be- 
fore; the second, third and fourth patients had been 
bitten six, four and two days previously, and were in 
character mild, severe and mild respectively. In writ- 
ing to Dr. Reed that night of the incident, I remarked 



126 Insects and Disease 

jokingly that if there was anything in the mosquito 
theory, I should have a good dose. And so it happened. 
After having slight premonitory symptoms for two 
days, I was taken sick on August 31, and on Septem- 
ber 1, I was carried to the yellow fever camp. My life 
was in the balance for three days, and my chart shows 
that on the fifth, sixth and seventh days my urine con- 
tained eighth-tenths and nine-tenths of moist albumin. 
On the day I was taken sick, August 31, 1900, Dr. La- 
zear applied the same mosquito, with three others, to 
another individual who suffered a comparatively mild 
attack and was well before I had left my bed. It so 
happened that I was the first person in whom the mos- 
quito was proved to convey the disease. 

"On the eighteenth of September, five days after I 
was permitted to leave my bed, Dr. Lazear was stricken, 
and died in convulsions just one week later, after sev- 
eral days of delirium with black vomit. Such is yellow 
fever. 

u He was bitten by a stray mosquito while applying 
the other insects to a patient in one of the city hospitals. 
He did not recognize it as a Stegomyia, and thought 
it was a Culex. It was permitted to take its fill and he 
attached no importance to the bite until after he was 
taken sick, when he related the incident to me. I 
shall never forget the expression of alarm in his eyes 
when I last saw him alive in the third or fourth day 
of his illness. The spasmodic contractions of his dia- 
phragm indicated that black vomit was impending, and 



Mosquitoes and Yellow Fever 127 

he fully appreciated their significance. The dreaded 
vomit soon appeared. I was too weak to see him again 
in that condition, and there was nothing that I could 
do to help him. 

"Dr. Lazear left a wife and two young children, one 
of whom he had never seen." 

These experiments and many others like them 
conducted on soldiers and Spanish immigrants 
proved that this particular mosquito would trans- 
mit the disease under certain conditions. 

1. The mosquito must bite the patient during 
the first three days of the fever; after that a yellow 
fever patient cannot infect a mosquito. 

2. A period of twelve days must elapse before 
the mosquito is able to infect another person. 
After that she may infect anyone she may bite; 
that is, the germs remain virulent during the rest 
of the mosquito's life. The French Yellow Fever 
Commission working in Rio de Janeiro claim that 
the first generation of offspring from such an in- 
fected mosquito is capable of causing the disease 
after they are fourteen days in the adult condition. 

The next step was to ascertain whether the dis- 
ease could be contracted in any other way than by 
/ the bites of infected mosquitoes. A camp named 
Camp Lazear was established and the following 
tests made : A mosquito-proof building of one room 



128 Insects and Disease 

was completely divided by a wire screen from floor 
to ceiling. In one room fifteen mosquitoes that 
had previously bitten yellow fever patients and had 
undergone the proper period of incubation were 
liberated. In this room a non-immune exposed 
himself so that he was bitten by several of the in- 
sects. A little later the same day and again the 
next day the mosquitoes were allowed to feed on 
him for a few minutes. Five days later, the usual 
incubation period, he developed yellow fever. 

At the same time that he entered the building 
two other non-immunes entered the other compart- 
ment where they slept for eighteen nights separated 
from the mosquitoes by the wire screen. They 
showed no signs of taking the fever. 

In another mosquito-proof house two soldiers 
and a surgeon, all non-immunes, lived for twenty- 
one days. From time to time they were supplied 
with soiled articles of bedding, clothing, etc., di- 
rect from the yellow fever hospital in the city. 
These articles had been soiled by the urine, fecal 
matter and black vomit obtained from fatal and 
other cases of yellow fever. These articles were 
handled and shaken daily, but no diseas j developed 
among the men and at the end of th twenty-one 
days, two other non-immunes relieved them and 
handled a new supply of clothing in the same way, 



Mosquitoes and Yellow Fever 129 

sleeping between the same sheets that had been 
used by a patient dying of yellow fever and expos- 
ing themselves in every possible way to the soiled 
clothing. But no disease developed. That these 
men were susceptible was shown later by inocu- 
lating some of them, when they developed the 
disease. 

In another experiment certain men in a camp 
allowed themselves to be bitten by mosquitoes that 
had passed through the proper period of incuba- 
tion and every one of them and no others con- 
tracted the disease. It was also shown that a mos- 
quito was capable of communicating the disease 
as long as fifty-seven days after it had bitten a 
yellow fever patient. Another set of experiments 
showed that a subcutaneous injection into a non- 
immune of a very small quantity of blood from the 
veins of a yellow fever patient in the first two or 
three days of the disease would produce the fever. 

SUMMARY OF RESULTS 

Since that time much other work has been done 
by independent workers as well as by French and 
English Commissions both working at Rio de 
Janiero. 3 3?he results of their investigation are 
practically 3ko same and may be summed up as 
follows : 



130 Insects and Disease 

1. The virus of the yellow fever is in the blood- 
plasma, not in the corpuscles, for these may be re- 
moved and the plasma still be infective. 

2. The virus is conveyed from one patient to an- 
other by the yellow fever mosquito, Stegomyia 
calopus, and in no other way except by experi- 
mental injections. 

3. The patient is a source of infection only dur- 
ing the first three or four days of the disease (this 
after the three to six days of incubation). 

4. The virus must undergo an incubation period 
of twelve to fourteen days in the mosquito before 
she is capable of transmitting the disease. 

5. The parasite, whatever it is, has never been 
seen. It is probably too small to be seen by any 
of our present microscopes, even the recently in- 
vented ultramicroscope. It is probably not a bac- 
terial parasite but very likely a Protozoan, and cer- 
tain specialists have even shown by the study of 
all the available data that it almost certainly be- 
longs to the Sporozoan genus Spirocheta. 

Now what does all this mean? It means the 
saving of hundreds of human lives annually. It 
means the banishing from many localities and 
possibly very soon from the face of the earth of a 
disease that since the earliest settlements on this 
continent has been a source of terror. It means 



Mosquitoes and Yellow Fever 131 

the making habitable of certain places which here- 
tofore a white man has entered only at the risk of 
his life. It means that quarantines need no longer 
be established when yellow fever breaks out in a 
district ; quarantines which have inevitably caused 
the loss of millions of dollars to the world of com- 
merce. 

RESULTS IN HAVANA 

The first practical work based on these findings 
was done in Havana. The Yellow Fever Commis- 
sion made their recommendations in 1900. In 
1901 and 1902 they were put into effect. The fol- 
lowing table of the death rate there during a period 
of ten years shows graphically the results : 



DEATHS IN HAVANA 


FROM YELLOW FEVER 




1893 


1894 


i895 


1896 


1897 


1898 


1899 


1900 


1901 


1902 


Jan. 


15 


7 


15 


10 


69 


7 


1 


8 


7 





Feb. 


6 


4 


4 


7 


24 


1 





9 


5 





Mar. 


4 


2 


2 


3 


3° 


2 


1 


4 


1 





Apr. 


8 


4 


6 


14 


7i 


1 


2 











May 


23 


16 


10 


27 


88 


4 





2 








June 


69 


3i 


16 


46 


174 


3 


1 


8 








July 


118 


77 


88 


116 


168 


16 


2 


3° 


1 





Aug. 


100 


73 


120 


262 


102 


16 


J 3 


49 


2 





Sep. 


68 


76 


135 


166 


56 


34 


18 


52 


2 





Oct. 


46 


40 


102 


240 


42 


26 


25 


74 








Nov. 


28 


23 


35 


244 


26 


13 


18 


54 








Dec. 


11 


29 


20 


147 


8 


13 


22 


20 









132 Insects and Disease 

As long as the United States held control at 
Havana the yellow fever was kept in check by 
fighting the mosquitoes, when this vigilance was 
relaxed the fever began to appear again and the 
Cubans found that it was necessary to keep up the 
fight against the mosquitoes if the island was to be 
kept free from the disease. 

THE FIGHT IN NEW ORLEANS 

In the summer of 1905 came another oppor- 
tunity to put the knowledge gained during these 
experiments to a practical test. Samuel Hopkins 
Adams in his article in McClure's Magazine, 
June, 1906, says of the beginning of this fight: 

''Eight years before, the mosquito-plague had in- 
fected the great, busy, joyous metropolis of the south. 
Ignorant of the real processes of the infection, New 
Orleans had fought it blindly, frantically, in an agony 
of panic, and when at last the frost put an end to the 
helpless city's plight, she lay spent and prostrate. The 
yellow fever of 1905 came with a more formidable and 
unexpected suddenness than that of 1897. It sprang 
into life like a secret and armed uprising in the midst 
of the city, full-fledged and terrible. But there arose 
against it the trained fighting line of scientific knowl- 
edge. Accepting, with a fine courage of faith that 
most important preventive discovery since vaccination, 



Mosquitoes and Yellow Fever 133 

the mosquito dogma, the Crescent City marshaled her 
defenses. This time there was no panic, no mob-rule 
of terrified thousands, no mad rushing from stunned 
inertia to wildly impractical action; but instead the 
enlistment of the whole city in an army of sanitation. 
Every citizen became a soldier of the public health. 
And when, long before the plague-killing frost came, 
the battle was over, New Orleans had triumphed not 
only in the most brilliant hygienic victory ever achieved 
in America, but in a principle for which the whole 
nation owes her a debt of gratitude." 

For some time the authorities had been trying 
to keep secret the fact that the disease was preva- 
lent, but the rapidity with which it spread made 
them realize that only united action on the part of 
all the community would be of any avail. The 
Citizens Volunteer Ward Organizations were or- 
ganized for the purpose of fighting the mosqui- 
toes which were everywhere. To many the fight 
looked hopeless. The miles of open gutters, the 
thousands of cisterns and little pools of standing 
water everywhere furnished abundant breeding- 
places for the mosquitoes. The ditches and ponds 
were drained or salted, the cisterns were screened, 
infected houses were fumigated, yet the fever con- 
tinued to spread. Rains refilled the ditches, winds 
tore the screens from the cisterns, the ignorant 



134 Insects and Disease 

people of the French quarter refused to cooperate. 
At last the city in desperation appealed to the 
President for aid. Surgeon J. H. White and a 
number of officers and men of the United States 
Public Health and Marine Hospital Service soon 
took charge of the work. This was continued 
along the same lines as before with the same ob- 
ject in view. But with the coming of the regulars 
the work was more systematically and thoroughly 
done. Every case of fever was treated as though 
it was yellow fever and every precaution taken 
to prevent mosquitoes from biting such a patient. 
The houses in which the fever occurred were 
thoroughly fumigated to kill any mosquitoes that 
might be there, and the neighborhood was thor- 
oughly searched to find any places where the mos- 
quitoes might be breeding. So confident were the 
authorities that the mosquito was the sole cause of 
the disease spreading, that besides fighting it no 
other work was undertaken save to make the sick 
as comfortable as possible. 

Finally the results began to be apparent. The 
number of cases gradually diminished, until long 
before frost came the city was free from the great 
pest. Yellow fever will doubtless appear from 
time to time in New Orleans and other cities, but 
there is, at least there should be, small danger of 



Mosquitoes and Yellow Fever 135 

another great epidemic, for the people now know 
how the disease is caused and the remedy. 

Not long since I had occasion to write to a 
prominent entomologist in Louisiana for some 
specimens of the yellow fever mosquito for labora- 
tory work. The following extract from his reply 
will show something of the work that is still being 
done there. 

"I am afraid we cannot furnish specimens of Steg- 
otnyia, in spite of the fact that Louisiana is supposed 
to be the most favorable home of this species in the 
South. Since the light occurrence of yellow fever in 
this State in 1905, a very vigorous war has been kept 
up against Stegomyia, and the ordinances of all Louis- 
iana cities and principal towns require the draining 
of all breeding places of this mosquito and the constant 
oiling or screening of all cisterns or other water con- 
tainers. The result is this species is very rare. Here 
in Baton Rouge I only see one once in a great while, 
and it would require perhaps a good many days' work 
at the present season to get as good specimens and as 
many of them as you require. " 

IN THE PANAMA CANAL ZONE 

Yellow fever was one of the worst obstacles that 
confronted the French when they were attempting 
to build the Panama Canal. The story of the 



136 Insects and Disease 

suffering and death from this dread disease there 
is most pathetic. Ship-load after ship-load of 
laborers were sent over, as those who had gone 
earlier succumbed to the fever. The contractors 
were responsible for their men while they were 
sick and in order to avoid having to pay hospital 
expenses the men were often discharged as soon 
as they showed signs of sickness. Many of them 
died along the roadside while endeavoring to 
reach some place where they could obtain aid. 
The ho^itals were usually filled with yellow fever 
patients, a very large percentage of whom died. 

Not only the day laborers suffered but many of 
the engineers, doctors, nurses and others sickened 
and died of the disease. It is reported that eighteen 
young French engineers came over on one vessel 
and in a month after their arrival all but one had 
died of the yellow fever. Out of thirty-six nurses 
brought over at one time, twenty-four died of the 
fever, and during one month nine members of the 
medical staff of one of the hospitals succumbed. 

One of the first things that the United States 
Government did in beginning work in the canal 
zone was to take up the fight against the yellow 
fever mosquito. In Panama where the water for 
domestic purposes was kept in cisterns and water- 
barrels, inspectors were appointed to see that all 



Mosquitoes and Yellow Fever 137 

such receptacles and other possible breeding-places 
for mosquitoes were kept covered. After the first 
inspection, 4,000 breeding-places were reported. 
About six months later there were less than 400. 
Similar work was done in all the towns and settle- 
ments along the route of the canal. In addition to 
this fight against the yellow fever mosquito con- 
siderable attention was paid to the breeding-places 
of the malarial mosquito. The results have been 
remarkable. Cases of yellow fever are now rare 
throughout this zone, and there has been a very 
great reduction in the extent of the malarial dis- 
tricts. The last case of yellow fever occurred in 
May, 1906. Before this work was done a man took 
his life in his hands when he went into this region. 
Now it is regarded as a perfectly safe place to live. 
Indeed it is a much safer place than many sections 
of our own country where proper sanitary measures 
have not been taken to protect the health of the 
community. 

IN RIO DE JANEIRO 

In Rio de Janeiro they have as yet been unable to 
get rid of the mosquitoes, although thousands of 
dollars are spent annually in fighting them. But 
the non-immunes there protect themselves by do- 
ing their business in Rio during the day and going 
back at night to Petropolis, twenty-five miles in- 



138 Insects and Disease 

land and twenty-five hundred feet higher, where 
they are safe, for no Stegomyia have ever been 
found there. 

They claim there that the yellow fever mosquito 
does not bite during the daytime after she has 
laid her eggs, and that she will not lay her eggs un- 
til about three days after she has fed on blood, 
therefore a Stegomyia that bites during the day 
will not carry the yellow fever because she is too 
young. This seems to explain why the fever can- 
not be contracted by being bitten by a mosquito 
in the daytime. Certain other experiments, how- 
ever, have given different results so that as far as 
we know it is not safe to be bitten at any time by 
such a mosquito in a region where the disease is 
endemic or where it is epidemic. 

In the main the work of the French Yellow 
Fever Commission working in Rio de Janiero has 
confirmed the findings of the American Com- 
mission. One interesting special thing that the 
French Commission seems to have established is 
that the female may transmit the infecting power 
to her offspring, so that it would be possible for 
a mosquito that had never bitten a yellow fever 
patient to be capable of infecting a non-immune 
person. While all this is very probable in the light 
of what we know of the disease and the way in 



Mosquitoes and Yellow Fever 139 

which other diseases caused by similar organisms 
may be transmitted by the parent to the offspring, 
yet the most conservative investigators are waiting 
for further proof. 

HABITS OF STEGOMYIA 

The whole fight against yellow fever, then is 
directed, as we have seen, against the mosquito, 
Stegomyia calopus. The habits of this species 
are such as to make it easy in some respects to 
combat. It is seldom found far away from human 
habitation. The adults will not fly far. Once in a 
house they usually stay there except when they 
leave to deposit their eggs. 

On the other hand, some of these same habits 
make it all the more dangerous. It will breed in 
almost any kind of water, no matter how filthy, and 
a very small amount will suffice. Thus any leaks 
from water-pipes or drains, cisterns, small cans of 
water or any such places may become dangerous 
breeding-places. If conditions are unfavorable 
there will often be developed small individuals 
which can easily make their way through ordinary 
mosquito-netting. 

Dr. Manson has pointed out an interesting 
possible result of the crusade that is now being 
waged against the yellow fever mosquitoes. The 



140 Insects and Disease 

immunity of the people native to the endemic 
regions is supposed to be due to their having had 
mild attacks of the fever during childhood, for the 
children in these regions are subject to certain 
fevers which are probably very mild forms of 
yellow fever. 

Now if we kill practically all of the Stegomyia 
so that these children do not have this fever there 
will be developed, in due time, a population most 
of whom are non-immune. 

This freedom from the disease for some time 
will allow us to grow careless in regard to fighting 
the mosquitoes. They will be allowed to increase 
and by some chance the yellow fever will again be 
introduced and there will then be very grave danger 
of most extensive and destructive epidemics. 

DANGER OF THE DISEASE IN THE PACIFIC 
ISLANDS 

I have already referred once or twice to the con- 
ditions in many of the Pacific tropical islands. 
In some of these various species of Stegomyia are 
abundant, and in some Stegomyia calopus is the 
most abundant and troublesome form. All the 
natives of these islands are non-immune because 
there has never been any yellow fever there. Un- 
less extraordinary care is taken the disease will be 



Mosquitoes and Yellow Fever 141 

introduced there sooner or later and the results 
are sure to be most appalling. The climatic and 
sanitary conditions and the habits of the people are 
ideal for the development and spread of the disease, 
and what I have seen of the conditions on some of 
these islands convinces me that it would be almost 
impossible to control the disease before it had a 
chance to kill a large percentage of the population. 

With the opening of the Panama Canal these 
things become more possible. Heretofore, the 
shipping to these regions has not been from ports 
where yellow fever was endemic or even likely to be 
epidemic. But unless the yellow fever is kept out 
of the canal zone, the danger will be many fold what 
it is now. 

The white man has already carried enough 
misery to these island peoples in the way of loath- 
some diseases, and it is to be hoped that this, an- 
other great curse, will not be carried to them with 
our civilization, the beneficial results of which 
have been so often very justly questioned. 

What I have said in regard to these islands ap- 
plies with equal force and in some instances with 
even greater force to parts of Asia, the Eastern 
Archipelago and other places. 




CHAPTER IX 

FLEAS AND PLAGUE 

LAGUE has always been one of the most 

dreaded diseases, and when we read of 

its ravages in the old world and the 

utter helplessness of the people before 

it we do not wonder that the very word rilled them 

with horror. One of the greatest scourges ever 

known began in Egypt about A. d. 542, and spread 

along the shores of the Mediterranean to Europe 

and Asia. It lasted for sixty years, appearing again 

and again in the same place and decimating whole 

communities. 

Another great pandemic, beginning in 1364, 

spread over the whole of the then known world and 

appeared in its most virulent form. On account 

of diffuse subcutaneous hemorrhages it came to be 

known as the " black death" and of course spread 

terror in all the communities where it appeared. 

Whole villages and districts were depopulated. 

The death-rate was very high, one authority placing 

the total mortality at twenty-five million. 

142 



Fleas and Plague 143 

During this time new centers of infection were 
established, and since then it has been carried by 
the commerce of the nations to all parts of the 
world. It is not restricted, as many other epidemic 
diseases, to the tropics or semi-tropics, although as 
a matter of fact we find it is more prevalent in these 
regions on account of the sanitary conditions. 

HOW PLAGUE WAS CONTROLLED IN SAN 
FRANCISCO 

Attention is called to these things in order that 
we may compare past conditions with present. 
During the last few years San Francisco has been 
fighting an outbreak of plague that in other days 
would have been nothing less than a national 
calamity. But with modern methods of handling 
it, based on knowing what it is, what causes it and 
how it is spread, the authorities there have been 
able not only to hold the disease in check, but 
practically to stamp it out with the loss of com- 
paratively few lives. 

Dr. Blue of the Public Health and Marine Hos- 
pital Service and his co-workers directed their 
whole energy toward controlling the rats. A small 
army of men were employed, catching rats in 
every quarter of the city. Dr. Rucker reports that 
fully a million rats were slain in this campaign. 



144 Insects and Disease 

Their breeding-places were destroyed by making 
cellars, woodsheds, warehouses, etc., rat-proof and 
removing all old rubbish. Garbage cans were in- 
stalled in all parts of the city, as it was required 
that all garbage be stored where rats could not feed 
upon it, and altogether every effort was made to 
make it as uncomfortable as possible for the rats. 

The marked success attending this work abun- 
dantly confirms the soundness of the theory upon 
which it was based, and serves as another example 
of the way in which science is teaching us how to 
prevent or control many of our most serious dis- 
eases. 

THE INDIAN PLAGUE COMMISSION 

In 1896, what proved to be a very serious out- 
break of plague, occurred in Bombay and spread 
to other parts of India. In 1898, a commission 
was appointed to inquire into the origin of the dif- 
ferent outbreaks, the manner in which the disease 
is communicated, etc. This was known as the 
Indian Plague Commission, and its exhaustive re- 
port, together with the minutes of the evidence 
presented to the committee, represents a stupen- 
dous amount of work on this subject and is the 
basis for much of the later investigation that has 
been undertaken. 



Fleas and Plague 145 

After the consideration of the evidence from 
various sources the commission decided that the 
principal mode of infection both for man and rats 
was through some sort of an abrasion in the skin, 
although it recognized also the possibility of in- 
fection through the nose and throat, and possibly, 
very rarely, through the intestinal tract or other 
places. 

Considerable time was spent in considering Dr. 
Simond's claim, made in 1898, that fleas which 
have been parasitic on plague-infected rats migrate 
on the death of their hosts and convey the infection 
to healthy men and rats. Dr. Simond sought to 
establish the following: 

"Firstly, that plague rats are eminently infective 
when infected with fleas and that they cease to be in- 
fective when they have been deserted by their parasites : 
Secondly, that living plague bacilli are found in asso- 
ciation with fleas which are taken from plague-infected 
rats: Thirdly, that plague can pass from infected rats 
to other animals which have not come directly in 
contact with them or with their infected excretions: 
Fourthly, that fleas which infest rats will transfer 
themselves as parasites to men." 

After reviewing the experiments which had been 
made to establish these claims the commission be- 
lieved that sufficient precaution had not been 



146 Insects and Disease 

taken to prevent infection from other sources and 
that not enough definite evidence was produced. 
Against this claim much negative evidence was 
considered and the final conclusion was "that suc- 
torial insects do not come under consideration in 
connection with the spread of plague.' ' 

In 1905 another body of men known as the Ad- 
visory Committee was appointed to arrange for 
further studies in India and other places, particu- 
larly in relation to the mode of dissemination of the 
disease. They at once appointed a new working 
commission who immediately began their studies 
and experiments. The preliminary reports of their 
work, which are still known as the Reports of the 
Indian Plague Commission, as well as the reports 
of contributing investigations that are being made 
from time to time, have served to establish entirely 
Dr. Simond's claims and have completely revolu- 
tionized the methods of fighting plague. 

There are several different types of plague, seem- 
ing to depend largely on the manner of infection. 
The most common type is that known as the bu- 
bonic plague which is characterized by buboes or 
swellings in various parts of the body. This form 
of infection is usually received through the skin 
in some manner or other. Only rarely does direct 
man-to-man infection occur though there is always 



Fleas and Plague 147 

the possibility of it. The investigations have 
shown that the flea is the most common agent in 
transferring the disease from rat to rat or from rat 
to man. This may be accomplished by the flea 
transferring the bacilli directly from one host to an- 
other on its proboscis, or they may be carried in the 
alimentary canal of the flea and gain an entrance 
into the skin through an abrasion of some kind 
when the flea is crushed as it is biting, or when some 
of the bacilli are left on the skin in the excreta of the 
insect. 

RESULTS OF VERJBITSKl'S EXPERIMENTS 

A very important series of experiments bearing 
directly on this subject was made in 1902 and 1903 
by Dr. D. T. Verjbitski. The paper giving the 
results of this work was not published in any 
scientific journal until 1908 when the Advisory 
Committee published it in one of their reports. 
The experiments were so well planned and exe- 
cuted and the results so definite that I think it is 
worth while to give in full his summary of results. 
The bugs referred to are bedbugs. 

" (1) All fleas and bugs which have sucked the blood 
of animals dying from plague contain plague microbes. 

"(2) Fleas and bugs which have sucked the blood 
of animals which are suffering from plague only con- 



148 Insects and Disease 

tain plague microbes when the bites have been inflicted 
from 12 to 26 hours before the death of the animals, 
that is, during that period of their illness when their 
blood contains plague bacilli. 

"(3) The vitality and virulence of the plague mi- 
crobes are preserved in these insects. 

" (4) Plague bacilli may be found in fleas from four 
to six days after they have sucked the blood of an 
animal dying with plague. In bugs, not previously 
starved or starved only for a short time (one to seven 
days), the plague microbes disappear on the third day; 
in those that have been starved for four to four and one- 
half months, after eight or nine days. 

"(5) The numbers of plague microbes in the in- 
fected fleas and bugs increase during the first few days. 

"(6) The faeces of infected fleas and bugs contain 
virulent plague microbes as long as they persist in the 
alimentary canal of these insects. 

"(7) Animals could not be infected by the bites of 
fleas and bugs which had been infected by animals 
whose own infection had been occasioned by a culture 
of small virulence, notwithstanding the fact that the 
insects may be found to contain abundant plague mi- 
crobes. 

" (8) Fleas and bugs that have fed upon animals 
which have been infected by cultures of high virulence 
convey infection by means of bites, and the more 
certainly so the more virulent the culture with which 
the first animal was inoculated. 



Fleas and Plague 149 

"(9) The local inflammatory reaction in animals 
which have died from plague occasioned by the bites 
of infected insects is either very slight or absent. In 
the latter case it is only by the situation of the pri- 
mary bubo that one can approximately identify the 
area through which the plague infection entered the 
organism. 

"(10) Infected fleas communicate the disease to 
healthy animals for three days after infection. Infected 
bugs have the power of doing so for five days. 

"(11) It was not found possible for more than two 
animals to be infected by the bites of the same bugs. 

"(12) The crushing of infected bugs in situ during 
the process of biting, occasioned in the majority of 
cases the infection of the healthy animal with plague. 

"(13) The injury to the skin occasioned by the bite 
of bugs or fleas offers a channel through which the 
plague microbes can easily enter the body and occasion 
death from plague. 

"(14) Crushed infected bugs and fleas and their 
faeces, like other plague material, can infect through 
the small punctures of the skin caused by the bites of 
bugs and fleas, but only for a short time after the in- 
fliction of these bites. 

"(15) In the case of linen and other fabrics soiled 
by crushing infected fleas and bugs on them, or by the 
fasces of these insects the plague microbes can under 
favorable conditions remain alive and virulent during 
more than five months. 



150 Insects aud Disease 

"(16) Chemical disinfectants do not in the ordinary 
course of application kill plague microbes in infected 
fleas and bugs. 

" (17) The rat flea Typhlopsylla musculi does not bite 
human beings. 

" (18) Human fleas do bite rats. 

"(19) Fleas found on dogs and cats bite both hu- 
man beings and rats. 

" (20) Human fleas and fleas found on cats and dogs 
can live on rats as casual parasites, and therefore can 
under certain conditions play a part in the transmis- 
sion of plague from rats to human beings, and vice 
versa." 

RESULTS OF VARIOUS INVESTIGATIONS 

Various other plague commissions from other 
countries as well as many individuals have in- 
vestigated the same subject, and the results all 
point conclusively to the fact that the rats and the 
fleas are at least the most important factors in the 
spread of the disease. The evidence from many 
sources and from many experiments may be briefly 
summed up as follows: The disease is caused by 
the presence in the system of minute bacteria, 
Bacillus pestis. It is probable that plague is pri- 
marily a disease of rats and only secondarily and 
accidentally, as it were, a disease of man. 

Rats are subject to the plague and are often 



Fleas and Plague 151 

killed by it in great numbers. An outbreak of 
plague among men is often preceded by a very 
noticeable outbreak among rats. 

Rats dying of the plague have their blood filled 
with the plague bacillus. Fleas or other suctorial 
insects feeding on such rats take myriads of these 
bacilli into their stomach and get many on their 
proboscis. 

The fleas usually leave a rat as soon as it dies 
and of course seek some other source of food. 
When such infected fleas are permitted to bite other 
rats or guinea-pigs these animals often develop the 
disease. Several of the species of fleas that infest 
rats will bite man also, and in the cases of many 
plague patients it can be definitely shown that they 
had recently been bitten by fleas. 

STRUCTURE AND HABITS OF FLEAS 

A study of the structure and habits of fleas shows 
that in many respects they are particularly adapted 
for spreading such a disease as bubonic plague. 
The piercing proboscis consists of three long needle- 
like organs, the epipharynx and mandibles, and a 
lower lip or labium. The mandibles have the sides 
serrate like a two-edged saw. The labium is di- 
vided close to its base so that it really consists of 
two slender four-segmented organs which lie close 



152 Insects and Disease 

together and form a groove in which the piercing 
organs lie. When the flea is feeding, the epi- 
pharynx and mandibles are thrust into the skin 
of the victim, the labium serving as a guide. As 
the sharp cutting organs are thrust deeper and 
deeper the labium doubles back like a bow and 
does not enter the skin. Saliva is then poured into 
the wound through minute grooves in the mandi- 
bles, and the blood is sucked up into the mouth by 
the sucking organ which lies in the head at the 
base of the mouth-parts. Just above this piercing 
proboscis is a pair of flat, obtuse, somewhat tri- 
angular pieces, the maxillary blades or maxillae. 
When the proboscis is fully inserted into the skin 
the tips of these maxillae may also be embedded in 
the tissue and perhaps help to make the wound 
larger. Attached to these maxillae is a pair of 
rather stout, four-jointed appendages, the palpi. 
They probably act as feelers. 

If the flea chances to be feeding on a plague- 
infected rat or person many of the plague bacilli will 
get on the mouth-parts and myriads of them are of 
course sucked up into the stomach with the blood. 
Those on the proboscis may be transferred directly 
to the next victim that it is thrust into, and those in 
the stomach may be carried for some time and 
finally liberated when the flea is feeding again or 




Fig. 105 — Rat-flea (Lcemopsylla cheopis); male. 




Fig. 106 — Rat-flea (L. cheopis); female. 




Fig. 107 — Head of rat-flea showing mouth-parts. 


/] 






/ n 






\ 


T*i4^ 


vmr 


■ 


V*=rC^H 


ifbr^Jy^ 













^/%* 


If 


if 


n 

/ 

r 



Fig. 108 — Human-flea (Pulcx irriians); male. 



Fleas and Plague 153 

when it is crushed by the annoyed host. The 
latter is probably the most common method of in- 
fection, for the bacilli that are liberated when the 
flea is crushed may readily be rubbed into the 
wound made by the flea bite or into abrasions of 
the skin due to the scratching. Kill the flea, but 
don't "rub. it in." 

During the recent outbreak in San Francisco 
many thousand fleas that were infesting man, rats, 
mice, cats, and dogs, squirrels and other animals 
have been studied and it has been found that while 
each flea species has its particular host upon which 
it is principally found, few if any of them will hes- 
itate to leave this host when it is dead and attack 
man or any other animal that may be convenient. 

COMMON SPECIES OF FLEAS 

Throughout India and in all the warm climates 
where plague frequently occurs the most common 
flea found on rats has come to be known as the 
plague flea (Lcemopsylla cheopus) (Figs. 105, 106), 
and is doubtless the principal species that is con- 
cerned in carrying the disease in those climates. 
It now occurs quite commonly on the rats in the 
San Francisco Bay region and is occasionally 
found there on man also. In the United States, 
Great Britain and other temperate regions another 



154 Insects and Disease 

larger species, Ceratophyllus fasciatus is by far 
the most common flea found on rats, and is com- 
monly known as the rat flea. It occurs on both 
the brown and the black rats M us norvegicus and 
M. rattus, on the house mouse and frequently on 
man. It has also been taken in California on 
pocket gophers and on a skunk. 

The common human flea (Pulex irritans) 
(Figs. 108, 109), is found in all parts of the in- 
habited world. Although we regard it primarily 
as a pest of human beings it often occurs very 
abundantly on cats, dogs, mice and rats as well as 
on some wild mammals such as badgers, foxes and 
others and has occasionally been found on birds. 

Most entomologists regard the fleas commonly 
found on cats and dogs as belonging to one species 
Ctenocephalus canis. Others believe them to be 
distinct species and call the cat flea Ctenocephalus 
jelis. So far as our personal comfort and safety 
is concerned it makes but little difference to us 
whether the flea that bites us is called canis or }elis 
for they both look very much alike, and act alike 
and the bite of one hurts just as much as the bite 
of the other. Although cats and dogs are their nor- 
mal hosts they are very often troublesome house- 
hold pests, sometimes making a house almost un- 
inhabitable. They are frequently found on rats, 



Fleas and Plague 155 

and therefore may carry the plague bacillus from 
rat to rat or from rat to man. 

GROUND-SQUIRRELS AND PLAGUE 

As early as 1903 Dr. Blue, in charge of the plague 
suppressive measures in San Francisco, became im- 
pressed with the possibility of the common Cali- 
fornia ground-squirrels (Otos pernio philus beecheyi), 
acting as an agent in the transmission of plague. 
It was rumored at that time that some epidemic 
disease was killing the squirrels in some of the 
counties surrounding San Francisco Bay, notably 
in Contra Costa County. None of the squirrels 
were examined at that time, but since then many 
thousand have been carefully studied and it has 
been definitely shown that many of them are plague- 
infected. Just how the plague got started among 
them will probably never be really known. There 
is little doubt, however, but that it was transferred 
in some way from the rats to the squirrels. The 
trains and the bay and river steamers running out 
from San Francisco would afford abundant oppor- 
tunity for the rats to go from the city to the ware- 
houses all along the shore. Once there they would 
use the same runways as the squirrels about the 
warehouses and in the near-by fields. In harvest 
time the rats migrate to the fields and make con- 



156 Insects and Disease 

stant use of the squirrel holes. The farmers in 
some sections report that they frequently catch 
more rats than squirrels in traps set in squirrel 
holes at that season of the year. 

This close association of the rats and the squir- 
rels affords a good opportunity for the fleas infest- 
ing them to pass from one host to the other. 

So far only two species of fleas have been re- 
corded from the ground-squirrels. One, Cerato- 
phyllus acutus, is very common, sometimes literally 
swarming over the squirrels, particularly if a squir- 
rel is sick or weak from any cause. The other spe- 
cies, Hoplopsyllus anomalus, is less abundant but 
still quite common. Both of these species infest 
rats also, so the chain of evidence is practically 
complete. We have only to assume that at some- 
time one or more of the plague-infected rats found 
their way into the region where the squirrels were, 
and the fleas passing from the rats to the squirrels 
would carry the plague with them. 

The fact that the plague already has such a start 
among the squirrels opens a new and very serious 
phase of the problem, of suppressing the disease. 
All who have hunted the ground-squirrels will 
testify to the readiness with which the fleas from 
them will bite those who are handling them. As it 
is the sick or weak squirrels that are most often 




Fig. 109 — Human-flea (P. irritans); female. 




Fig. 1 10 — Mouse-flea (Ctenopsyllus musculi); female. 



Fleas and Plague 157 

taken there is always a chance that plague may be 
transferred from them to human beings. The 
records of the plague cases in California show at 
least three cases in which there seems to be very 
little doubt that the disease resulted from handling 
plague-infected squirrels. 

A still more serious thing is the possibility of the 
disease remaining in a more or less virulent form 
among the squirrels for some time, possibly for 
years, and then breaking out again in some locality 
where the rats or men may become infected. As 
long as there is a trace of the disease among the 
squirrels there is always the chance of it spreading, 
so that new areas may become infested. Those in 
charge of the plague-suppressive measures are fully 
aware of these dangers and are making a careful 
study of the situation and will doubtless be able 
to cope with it successfully. It may be that the 
squirrels will have to be exterminated in the in- 
fected regions. This would be a long and difficult 
task, but the success attending the fight against the 
rats in a great city shows what can be done when 
the determination to do it is there. 

REMEDIES FOR FLEAS 

We have seen how a great city set to work to rid 
itself of the plague-sick rats. As a matter of fact 



158 Insects and Disease 

it was not the rats that they were after primarily. 
If the rats had not harbored fleas the city would 
have been glad to let the disease take its course and 
destroy as many rats as possible. But it was found 
that the only way to get rid of the fleas that might 
possibly be infected with the plague was to kill 
their rat hosts. 

General cleaning-up measures will of course 
very materially lessen the number of fleas about the 
private dwellings, but there often remains a num- 
ber of fleas in the house that are a source of great 
annoyance even if the danger is eliminated. 

Particularly is this apt to be so in places where 
cats or dogs are members of the household. These 
animals almost always harbor at least a few fleas, 
and where there are a few there is always a possi- 
bility, even a great probability, that there will be 
many more unless an effort is made to get rid of 
them. 

In some sections of the country it is the cat and 
dog flea that is the most troublesome to man. The 
minute white eggs of the fleas are usually laid about 
the sleeping-places of these animals and the slender 
active larvae that hatch from them feed upon any 
kind of organic matter that they can find in the 
dust or in the cracks and crevices. About eight or 
ten days after hatching the larvae spin delicate 



Fleas and Plague 159 

brownish cocoons in which they pass the pupal 
stage, issuing a few days later as the adult fleas. 

It will at once appear, then, that it is important 
to provide the cats and dogs with sleeping-places 
that can be kept clean. If they have a mat or 
blanket to sleep on this can be taken up and 
shaken frequently and the dust swept up and 
burned. In this way many of the eggs or larvae 
may be destroyed. Very often the dust under a 
carpet that has not been taken up and dusted for 
some time will be found to be harboring a mul- 
titude of fleas or their larvae. In such cases a 
thorough cleaning of the carpet and the floors will 
bring relief. Houses that are unused for some time 
during the summer months are often found to be 
overrun with fleas in the fall, for the fleas have had 
an unmolested opportunity to breed and multiply. 
Such rooms of course require a thorough cleaning 
or it is sometimes possible to kill the fleas by a lib- 
eral use of pyrethrum powder or benzine or to 
fumigate. In this connection, Dr. Skinner's note 
in the Journal 0} Economic Entomology is worth 
repeating. 

"In the latter part of last May (1908) I moved into a 
house that had not been previously occupied. No car- 
pet was used and being summer only a few rugs were 
placed on the floors. A part of the household consisted 



160 Insects and Disease 

of a collie dog and three Persian cats. Very soon the 
fleas appeared, the dog and cat flea, Ctenocephalus 
canis. I did not count them and I can't say whether 
they numbered a million or only a hundred thousand. 
On arising in the morning and stepping on the floor 
one would find from three to a dozen on the ankles. 
The usual remedies for fleas are either drastic or some- 
what unsatisfactory. The drastic one is to send the 
animals to the institutions, where they are asphyxiated, 
or take the other advice, * Don't keep animals.' 

"I tried mopping the floors with rather a strong 
solution of creolin but it did little good. Previous 
experience with pyrethrum was not very satisfactory. 
Knowing the volatility of naphthalene in warm weather 
and the irritating character of its vapor led me to try 
it. I took one room at a time, scattered on the floor 
five pounds of flake naphthalene and closed it for 
twenty-four hours. On entering such a room the 
naphthalene vapor will instantly bring tears to the eyes 
and cause coughing and irritation of the air passages. 
I mention this to show how it acts on the fleas. It 
proved to be a perfect and effectual remedy and very 
inexpensive, as the naphthalene could be swept up and 
transferred to other rooms. So far as I am concerned 
the flea question is solved and if I have further trouble 
I know the remedy. I intend to keep the dog and the 
cats." 




CHAPTER X 

OTHER DISEASES, MOSTLY TROPICAL, 
KNOWN OR THOUGHT TO BE TRANS- 
MITTED BY INSECTS 

SLEEPING SICKNESS 

NE of the worst scourges of Africa and 
one that is to-day attracting world- 
wide attention is the disease known as 
trypanosomiasis, the terminal phase of 
which is sleeping sickness, one of the most ghastly 
diseases that we know. 

Among the Protozoa referred to in one of the 
earlier chapters mention was made of certain try- 
panosomes which inhabit the blood of man and 
certain animals. Very little was known concerning 
these parasites previous to the beginning of the 
present century, but since that time several have 
been found to be of great economic importance. 
The group is being studied extensively and every 
day our knowledge of them is increasing so that 
we now know quite definitely the life-history of 
several. 

161 



1 62 Insects and Disease 

Trypanosoma lewisi, a parasite of rats, is per- 
haps the best known as it is always common where- 
ever rats are found. Sometimes as many as 30% or 
40% of the rats of certain districts are infected. 
It is thought that these are transmitted from rat to 
rat by the common rat-louse which serves as an 
intermediate host. Fleas may also act as dissem- 
inating agents. 

A few other kinds cause serious disease of ani- 
mals, but we are more interested just now in the 
particular one that is causing so much trouble in 
Africa. This parasite was discovered in 1902 and 
was named Trypanosoma gambiensi (Fig. in). 
Since then it has been found to be widely dis- 
tributed. Although the natives have doubtless long 
been subject to the disease caused by this parasite, 
the recent influx of whites to these regions and 
the consequent movements of the natives have 
caused a great spread of the disease so that whole 
regions are now made desolate, the inhabitants 
dying or fleeing to escape the uncanny death. 

The disease may run its course in a few months 
or it may take years. The symptoms are various, 
but infection is usually soon followed by fevers, 
sometimes mild, sometimes severe, which recur at 
irregular intervals. Certain glands or other parts 
of the body may become swollen. More or less 



Other Diseases Transmitted by Insects 163 

extensive skin eruptions occur on all parts of the 
body and the patient gradually becomes anemic 
and physically and intellectually feeble. The 
nervous system seems to be affected by the para- 
site, either directly or by the action of the toxins 
it produces. The patient becomes more debili- 
tated and morose with an increasing tendency 
to sleep, hence the name sleeping sickness. As 
the stupor deepens the patient looses all desire 
or power of exertion and as little food is taken 
he rapidly wastes away and finally succumbs 
for after this final stage is reached there is no re- 
lief. 

It is definitely known that a species of tsetse- 
fly, Glossina palpalis (Fig. 112), which somewhat 
resembles our stable-fly, is responsible for the 
dissemination of the disease, and some recent in- 
vestigators have suggested that certain species of 
mosquitoes may also carry the parasite from one 
host to another. There still remains some doubt 
as to the exact manner in which the fly transmits 
the disease, but it seems altogether likely that it is 
an alternative host and does not serve as a simple 
mechanical carrier. In this respect it is like the 
mosquito which is one of the necessary hosts of 
the malaria parasites, and unlike the house-fly 
which carries the germs of various diseases in a 



164 Insects and Disease 

purely mechanical way without serving as a definite 
necessary host for the parasite. 

The tsetse -fly is found only in tropical Africa 
and is limited in its distribution there to certain 
very definite, narrow, brushy areas along the water's 
edge. If these places can be avoided there seems 
to be little danger. Those who are fighting the dis- 
ease have found that if the brush in the vicinity of 
watering-places and ferry-landings is cleared away 
such places become comparatively safe. These 
flies do not lay eggs but produce full-grown larvae 
which soon pupate in the ground. 

ELEPHANTIASIS 

In many tropical regions human blood as well as 
that of other animals is the normal habitat of cer- 
tain worm-like parasites (Nematodes). They are 
not entirely confined to the tropics but may ex- 
tend far up into the subtropical regions. Five or 
six different species of these parasites are known, 
only one of which, however, has been shown to be 
of any pathological importance, as far as human 
beings are concerned. 

This species, Filaria bancrojti, is not only very 
widely distributed, but in regions such as some of 
the South Sea Islands a very large per cent of the 
natives have the filariae present in their blood. 




Fig. hi — Trypanosoma gamblense; various forms from 
blood and cerebrospinal fluid. (After Manson.) 




Fig. 112 — Tsetse-fly. (After Manson.) 



Other Diseases Transmitted by Insects 165 

When these parasites are withdrawn from the circu- 
lation and placed on a slide for study they are seen 
to be minute transparent, colorless, snake-like or- 
ganisms inclosed in a very delicate sack or sheath. 
They are but a little more than one-hundredth of 
an inch long and about as big around as a red 
blood-corpuscle. These are the larval forms of the 
parasite and have been called by Le Dantec the 
micro-filaria. 

If blood of the patient drawn from the skin, is 
examined during the day few if any of these para- 
sites are found, but if it is examined between five 
or six o'clock in the evening and eight or nine 
o'clock the next morning they may be found in 
numbers. During the daytime they have retired 
from the peripheral circulation to the larger arter- 
ies and to the lungs, where they may be found in 
great numbers. 

This night-swarming to the peripheral circu- 
lation has been found to be a remarkable adapta- 
tion in the life-history of the parasite, for it has been 
demonstrated that in order to go on with its de- 
velopment these larval forms must be taken into 
the alimentary canal of the mosquito. Most of the 
mosquitoes in which the development takes place 
are night-feeders, so that the parasites are sucked 
up with the blood of the victim. Once inside the 



1 66 Insects and Disease 

stomach they soon free themselves from the in- 
closing sheath and make their way through the 
walls of the stomach and enter the muscular tissue, 
particularly the thoracic muscles. Here they un- 
dergo a metamorphosis and increase enormously in 
size, some attaining one-sixteenth of an inch in 
length. 

After sixteen to twenty days they leave these 
muscles and make their way to other parts of the 
body. A few may be found in different parts of the 
abdomen, but most of them make their way forward 
into the head of the mosquito and coil themselves 
up close to the base of the proboscis, finally finding 
their way down into the proboscis inside the la- 
bium. Here they lie until an opportunity offers for 
them to escape to the warm blood of a vertebrate. 
They probably pass through the thin membrane 
connecting the labella with the proboscis and there 
find their way into the wound made by the punc- 
ture when the insect bites. Whether these para- 
sites can gain an entrance into the circulatory 
system in any other way is not known. It has been 
suggested that the mosquitoes dying and disinte- 
grating on the surface of water may liberate the 
filarial which may later find their way into the 
system of the vertebrate host when the water is 
used for drinking, but most of the investigations 



Other Diseases Transmitted by Insects 167 

made so far seem to indicate that they make their 
way directly from the proboscis into the new host. 

Soon after entering the circulatory system of the 
human host the parasites make their way into the 
lymphatics where they attain sexual maturity, and 
in due time new generations of the larval filariae 
or microfilariae are poured into the lymph, and 
finally into the definite blood-vessels, ready to be 
sucked up by the next mosquito that feeds on the 
patient. 

In most cases of infection the presence of these 
filariae in the blood seems to cause no inconvenience 
to the host. They are probably never injurious in 
the larval stage, that is, in the stage in which they 
are found in the peripheral circulation. 

In many cases, however, the presence of the 
sexual forms in the lymphatics may cause serious 
complications. The most common of these is that 
hideous and loathsome disease known as elephan- 
tiasis in which certain parts of the patient becomes 
greatly swollen and distorted. An arm or a leg 
may become swollen to several times its natural 
size, or other parts of the body may be seriously 
affected. 

In some of the South Sea Islands 30% to 40% of 
the natives are afflicted in this way, some only 
slightly others seriously. There is little or no pain, 



1 68 Insects and Disease 

but in severe cases the distorted parts often render 
the patient entirely helpless. 

The exact way in which the parasites cause such 
swelling is not very definitely known. Manson, 
who has done more work on these diseases than 
any one else, believes that the trouble arises from 
the clogging of the lymphatic glands or trunks, 
thus cutting them off from the general circulation, 
in which case the affected parts may become dis- 
torted. This clogging of the passages is believed 
to be due to the presence of great numbers of im- 
mature eggs which have been liberated by para- 
sites injured in some way before their eggs were 
entirely developed. 

This interference with the lymphatic circulation 
brings about the anomalous condition of a patient 
with a serious filarial disease with fewer of the 
filarial parasites in his blood than one who is not 
so seriously affected. This is supposed to be due 
to the fact that the disease-producing parasites 
have died and that the lymphatics have become so 
obstructed that any microfilariae they may contain 
cannot make their way into the general circulation. 
Such a patient then would not be as likely to infect 
a mosquito as would one less seriously affected. 

It has always been thought that little or nothing 
could be done in the way of successfully treating 






Other Diseases Transmitted by Insects 169 

this disease, but quite recently a French physician, 
who has been conducting a long series of experi- 
ments in the Society Islands, announced that he is 
able to cure many cases by certain surgical opera- 
tions on the affected parts. 

DENGUE OR " BREAKBONE FEVER " 

This is another disease of the tropics often occur- 
ring in widespread epidemics. It is probably most 
frequently met with in the West Indies, but may 
occur in any of the tropical countries or islands. 
Occasionally it spreads into subtropical or even 
temperate regions. Several extensive epidemics 
have occurred in the United States. Once intro- 
duced into a community it spreads very rapidly 
and nothing seems to confer immunity. 

The various names by which it has been called 
well describe its effect on the patient; breakbone 
fever, dandy-fever, stiff-necked or giraffe-fever, 
boquet (or " bucket") fever, scarlatina rhewmatica, 
polka-fever, etc. While the suffering is intense as 
long as the disease lasts it seldom terminates 
fatally. 

It has always been classed as a very contagious 
disease and it has not yet been definitely shown 
that it is not. Recent observations, however, have 
shown that it is probably caused by a certain 



170 Insects and Disease 

Protozoan parasite that is found in the blood of 
dengue patients and several experiments have been 
conducted by Dr. Graham which seem to indicate 
that it is transmitted by mosquitoes. In these ex- 
periments, Culex jatigans, a common tropical or 
subtropical mosquito, was used. The same para- 
site that is found in the human blood may be found 
in the stomach and blood of the mosquitoes up to 
the fifth day after it has fed on a dengue patient. 

Sick and healthy individuals were allowed to re- 
main in close contact in a room from which the 
mosquitoes had been excluded, and the disease was 
not spread. Mosquitoes that had bitten dengue 
patients were taken to a higher region where 
dengue had never occurred and allowed to bite two 
healthy persons. Both developed the disease and 
as they were protected from other mosquitoes until 
they had recovered, the disease did not spread to 
others of the community. These and other ob- 
servations seem to make a complete chain of evi- 
dence, and most medical men to-day accept the 
theory as well proved and in their practice take 
every precaution to prevent the spread of the 
disease by keeping the infected patient from being 
bitten by the mosquitoes. 

The yellow fever mosquito is also suspected of 
carrying this same disease, and it is possible that 



Other Diseases Transmitted by Insects 171 

other species are also concerned. If it is true that 
the parasite can be carried by several different 
species of mosquitoes this would account very 
largely for its rapid spread wherever it is intro- 
duced into a community. Where it occurs outside 
the tropics it is only in the warm summer months 
when mosquitoes are always abundant. 

MALTA OR MEDITERRANEAN FEVER 

This is also a tropical and subtropical disease 
that occasionally gets up into the temperate region, 
sometimes occurring in the United States. The 
fever begins with a severe headache, and other 
symptoms follow. It is usually of the remittent 
type and may continue for some months. 

It is caused by minute bacteria {Micrococcus 
melitensis) and is a very infectious but not usually 
contagious disease. The germ is readily conveyed 
by inoculation, and several investigators have 
sought to show that the mosquito often serves as 
the inoculating agent. The disease is especially 
prevalent during the mosquito season, and has 
twice been conveyed to monkeys by infected in- 
sects. 

LEPROSY 

This loathsome disease has long been known to 
be caused by a particular bacillus (Bacillus lepra), 



172 Insects and Disease 

but the way in which this organism gains an 
entrance into the system is still unknown. Many 
theories have been propounded, but none of them 
has been well established. Within recent years 
the possibility of insects carrying the germ and in 
one way or another transmitting it to healthy in- 
dividuals has been suggested and much discussed. 
As the leprae bacilli are present in the skin and 
ulcers of leprous patients, insects sucking the blood 
or feeding on the sores could not help taking some 
of them into their body or becoming contaminated. 
These bacilli have been found at various times in 
the stomach or intestine of mosquitoes, fleas and 
bedbugs. So it is believed by some that these and 
other insects, such as lice and flies, may sometimes 
transmit the disease. On a previous page we have 
referred to the possibility of the face-mites acting 
as disseminators of leprosy. 

Leprosy occurs most commonly among people 
where little attention is paid to bodily cleanliness. 
Such people are usually freely infested with various 
parasites that thrive well in the filth, so if the germs 
can be transmitted in this way the carriers are 
there in abundance. 

The fact that the sores usually occur on exposed 
parts of the body has been pointed to as evidence 
that inoculation is due to such insects as flies and 



Other Diseases Transmitted by Insects 173 

mosquitoes. It has been noted that leprosy is fre- 
quently very common in regions where elephantia- 
sis occurs, suggesting the possibility of the same 
carrier, the mosquito, for both diseases. So while 
there is as yet very little evidence one way or the 
other, insects that are found around leprous pa- 
tients are to be regarded with suspicion, for until 
we know more definitely just how the disease is 
communicated the insects must be looked on as 
possible sources of contamination. 

KALA-AZAR OR DUM-DUM FEVER 

This is a very fatal infectious disease of many 
tropical and subtropical regions, spreading terror 
among the natives wherever it occurs. It is caused 
by the presence in the system of Protozoan para- 
sites, the so-called Leishman-Donovan bodies, that 
have recently been studied by several observers. 

Dr. W. S. Patton of the Indian Medical Service 
has been making some extensive experiments with 
the common bedbug of India (Cimex rotundatus) 
which seem to demonstrate fully that this insect is 
responsible for the transmission of the parasite that 
causes the disease. He has found the parasite in 
all stages of development in the bedbug. This, 
taken with a number of other observations in re- 
gard to the tendency of the disease to cling to par- 



174 Insects and Disease 

ticular houses, makes a strong case against the bed- 
bug. Manson, however, believes that the parasite 
may be transmitted by other agents also, possibly 
by means of flies that visit the sores or in other 
ways. 

ORIENTAL SORE 

This disease, once supposed to be confined to the 
Orient, is now found to be rather widely distributed 
throughout the tropics, where it is sometimes very 
prevalent. It is caused by the presence in the 
system of a parasite very similar to or identical 
with the one causing kala-azar and is regarded by 
some as a modified form of that disease. The 
patient is affected with one or more serious sores 
or ulcers which usually occur on exposed parts of 
the body. 

The parasite that causes the disease is supposed 
to be carried by insects either directly or indirectly. 

In the latter case the insect may act as an inter- 
mediate host. 

Dogs and camels are also attacked by this disease 
and may be sources of infection. 




BIBLIOGRAPHY 

COMPLETE list of books and articles 
dealing more or less directly with the sub- 
jects discussed in this book would be too 
extended for use here. For the past ten or 
twelve years many of the medical and biological jour- 
nals have contained articles in almost every issue, dis- 
cussing these subjects in some of their phases. I have 
selected only a few of the more important of them, and 
these only the English ones, confining myself mostly to 
those that I have personally consulted, and giving brief 
annotations. Many of these will be found to include 
very full bibliographies of the particular subject treated. 
In order to avoid repetition, references are given under 
one head only although many might properly be in- 
cluded in other sections as well. 

PARASITES AND PARASITISM 

Braun, Max. Animal Parasites of Man. Translated by 
Pauline Falcke and edited by L. W. Sambon and F. V. Theo- 
bald. Third edition, 1906. A chapter on the general sub- 
ject of parasitism and a description of parasites of all classes. 
Bibliography. 

Leuckart, R. The Parasites of Man and the Diseases In- 
duced by Them. Eng. transl., London, 1886. 
i75 



176 Insects and Disease 

Neuman, Theo. Entoparasites and Hygiene. Trans. Vassar 
Bros. Institute, VII, 1895. A general discussion of parasitism; 
life-history of some common parasites that infest man. 

Neumann, L. G. Treatise on the Parasites and Parasitic Diseases 
of the Domesticated Animals. Eng. transl. by Fleming, 1892. 

Ransom, B. H. How Parasites Are Transmitted. Year Book 
U. S. Dept. Agric, 1905, pp. 139-166 (pub. 1906). Discusses 
the ways in which parasites of all classes are transmitted. 

Sambon, L. The Part Played by Metazoan Parasites in Tropi- 
cal Pathology. Jour. Trop. Med. & Hyg., Vol. XI, Jan. 15, 
1908. A comprehensive discussion of this subject. 

Shipley, A. E., and Fearnsides, E. G. Effects of Metazoan 
Parasites on Their Hosts. Jour. Econom. Biology, Vol. I, 

1906, pp. 41-62. Discusses injury due to mere presence of 
parasite in host; to the migration of the parasite; loss to host 
by feeding of parasites; injury by certain toxins. 

Stiles, C. W. Diseases Caused by Animal Parasites. Osier's 
Mod. Med., Vol. I, 1907, p. 525. General discussion; Tre- 
matodes; Cestodes; Roundworms; Acariasis; Parasitic Insects; 
Myiasis. 

Van Beneden, P. J. Animal Parasites and Messmates. 1889. 
Contains much that is interesting. 

Ward, Henry B. Influence of Parasitism on the Host. Proc. 
Amer. Assn. for Advancement of Science, Vol. 56, 1907. A 
comprehensive statement of this subject. List of literature. 

PROTOZOA 

Calkins, G. N. The Protozoa. Osier's Mod. Med., Vol. I, 

1907, p. 353. General notes on the Protozoa; classification; 
reproduction; life-cycle of various forms. Regards Protozoa as 
subkingdom and the four great divisions as phyla. 

Calkins, G. N. Protozoology. N. Y., 1909. Chapters on 
parasitism, pathogenic Protozoa, etc. 



Bibliography 177 

Clarke, J. J. Protozoa and Disease. London, 1903, Pt. I. 
Discusses the various protozoa that cause disease, and refers 
frequently to those that are transferred from host to host by 
insects. 

Clarke, J. J. Protozoa and Disease. London, 1908. Part II, 
comprising sections on the causation of smallpox, syphilis and 
cancer. Notes on parasitic Protozoa, tropical diseases, ticks, 
piroplasmosis, etc. 

Daniels, C. W. Persistence of the Tropical Diseases of Man 
Due to Protozoa. Jour. Trop. Med. &Hyg., 12, Aug. 2. 1909, 
pp. 232-234. Same in Lancet, II, 1909, p. 460. Good sum- 
mary of present knowledge of the subject. 

Minchin, E. A. Protozoa. In Albutt and Rolleston's System 
0} Medicine, II, 1907, pp. 9-122. A comprehensive chapter 
on Protozoa. Many parasitic forms are figured and described. 
Bibliography. 

Minchin, E. A. The Sporozoa. In Lankester's Treatise on 
Zool., Pt. I, pp. 150-360, 1903. Best account of this group, 
list of Sporozoan hosts. Bibliography. 

BACTERIA 

Flexner, Simon. Relation of Bacteria and Sporozoa to Dis- 
ease. Science, N. S., Vol. 27, No. 682, pp. 133-136. On 
these pages discusses relation of bacteria and Protozoa to 
human diseases. 

Jordan, Edwin O. General Bacteriology. Philad., 1898. A 
good general treatment of the subject. 

Levy, Ernst, and Klemperer, Felix. Elements of Clinical 
Bacteriology for Physicians and Students (transl. by A. A. 
Eschner), Philad., 1909. Morphology and biology of bacte- 
ria; infection; immunity; specific diseases of bacterial origin, 
etc. 

Muir, Robt., and Ritchie, Jas. Manual of Bacteriology. 



178 Insects and Disease 

N. Y., 1903. Contains chapter on the relation of bacteria to 
diseases and discussion of several bacterial diseases. 
Sternberg, G. M. A Manual of Bacteriology. N. Y., 1893. 
Part III is devoted to pathogenic bacteria. 

INSECTS AND DISEASE 

Herms, W. B. Medical Entomology, Its Scope and Methods. 
Jour, of Eco. Ento., Vol. 2, No. 4, 1909, pp. 265-268. 

Howard, L. O. Insects as Carriers and Spreaders of Disease. 
Year Book U. S. Dept. Agric, 1901, pp. 177-192. Good re- 
view of the subject. 

Howard, L. O. How Insects Affect Health in Rural Districts. 
U. S. Dept. Agric, Farmers' Bulletin, No. 155, 1902. Dis- 
cussion of city and county conditions; protection from typhoid, 
malaria and yellow fever. 

Howard, L. O. Economic Loss to the People of U. S. Through 
Insects That Cause Disease. Bull. 78, U. S. Dept. Agric. 
Bur. 0} Ent., 1909. A comprehensive discussion and summary 
of the subject. Discusses mosquitoes, flies, the Panama Canal, 
epidemic diseases and the progress of nations. 

Kellogg, V. L. Insects and Disease, Chap. XVIII, in Ameri- 
can Insects, pp. 615-654, 1905. Discusses Mosquitoes and 
malaria; yellow fever and filariasis. 

King, H. H. Report on Economic Entomology of Khartoum, 
in Third Rept. 0} Wellcome Research Lab., 1908. Discusses 
insects injurious to man: mosquitoes, blood-sucking insects 
other than mosquitoes, etc. 

Mason, C. F. The Spread of Diseases by Insects, with Sug- 
gestions Regarding Prophylaxis. International Clinics, Vol. II, 
1904, pp. 1-2 1. A brief summary of the subject. 

McCrae, John. Recent Progress in Tropical Medicine. In- 
ternational Clinics, Vol. II, 1904, pp. 22-36. Discusses several 
diseases, some of which are transmitted by insects. 



Bibliography 179 

NuTTAii, G. H. F. On the Role of the Insects xArachnids and 
Myriapods as Carriers in the Spread of Bacterial and Parasitic 
Diseases of Man and Animals. A critical and historical study. 
Johns Hopkins Hospital Reports, Vol. 8, 1899, pp. 1-154. 
A review of all the literature up to this date. Important 
article. 

Xuttall, G. H. F. Insects as Carriers of Disease. Recent ad- 
vances in our knowledge of the part played by blood-sucking 
arthropods (exclusive of mosquitoes and ticks) in the trans- 
mission of infectious diseases. Bericht iiber den XIV. Intern. 
Kongress fur Hygiene und Dermogrophic. Berlin, 1907, 
pp. 195-206. Discusses protozoan and bacterial diseases. 

Stiles, C. W. Insects as Disseminators of Disease. Virginia 
Medical Semi-monthly, Vol. 6, Xo. 3, May 10, 1901, pp. 53-58. 
Good statement of subject with list of recent workers. 

Wherry, W. B. Insects and Infection. Cat. State Jour, of 
Med., Nov., 1907. Discusses the role of insects, ticks, etc., 
in the transmission of infectious diseases. 

Symposium on Yellow Fever and Other Insect-borne Diseases. 
Science, X. S., Vol. 23, Xos. 584-585, 1906. The Protozoan 
Life-cycle, G. X. Calkins. Filariasis and Trypanosome Dis- 
eases, H. B. Ward. The Practical Results of Reed's Findings 
on Yellow Fever Transmission, J. H. White. Difficulties of 
Recognition and Prevention of Yellow Fever, Q. Kohnke. 
The Practical Side of Mosquito Extermination, H. C. Weeks. 
Without Mosquitoes There Can Be Xo Yellow Fever, Jas. 
Carroll. Estivo-autumnal Fever, Cause, Diagnosis, Treat- 
ment and Destruction of Mosquitoes Which Spread the Dis- 
ease, H. A. Veazie. 

MOSQUITOES— SYSTEMATIC AXD GENERAL 

Balfour, Andrew, and Staff. Second Report of the Wellcome 
Research Laboratories at the Gordon Memorial College, Khar- 



180 Insects and Disease 

toum, 1906. Includes reports on work on mosquitoes and 
other noxious insects. 

Boyce, Sir Robekt W. Mosquitoes or Man? The Conquest 
of the Tropical World. N. Y., 1909. Reviews medical and 
sanitary work in the tropics and discusses the relation of insects 
to various tropical diseases. 

Busch, August. Report on a Trip for the Purpose of Studying 
the Mosquito Fauna of Panama. Smith. Miscell. Coll., Vol. 5, 
Pt. I, 1908, p. 49. Work that is being done in Panama to 
control the mosquitoes. Annotated list of species. 

Felt, E. P. Mosquitoes or Culicidae of New York State. In 
N. Y. Slate Museum Bull. 79, Entomology 22, 1904. Dis- 
cusses distribution, migration and life-history of various species 
of mosquitoes and mosquito diseases. Bibliography. 

Giles, Geo. M. A Handbook of Gnats or Mosquitoes, Giving 
the Anatomy and Life-History of the Culicidae. London, 1902. 
Whole subject treated very fully. 

Grubbs, S. B. Vessels as Carriers of Mosquitoes. Pub. Health 
and Mar. Hospt. Ser. Bull. 11, Mar. 3, 1903. Believes that 
mosquitoes may come aboard when the vessel is lying at anchor 
one-half mile from shore, and that under favorable conditions 
they may come aboard when the vessel is fifteen miles from 
shore. 

Howard, L. O. Mosquitoes. Osier's Mod. Med., Vol. I, p. 370, 
1907. General notes on classification and habits particularly 
in relation to diseases. 

Howard, L. O. Notes on Mosquitoes of the United States. 
U. S. Dept. Agric, 1900. Div. of Ento. Bull. No. 25, N. S. 
Account of the structure; biology; remarks on remedies. 

Howard, L. O. Concerning the Geographic Distribution of 
the Yellow Fever Mosquito. Public Health Rept., Pub. 
Health and Mar. Hospt. Ser. t Nov. 13, 1903. The same re- 
vised to Sept. 10, 1905. 

Howard, L. O. Mosquitoes: How They Live; How They Carry 



Bibliography 181 

Disease; How They Are Classified; How They May Be De- 
stroyed. N. Y., 1901. One of the best popular books on 
mosquitoes. 

McCracken, I, Anopheles in California, with a Description 
of a New Species. Entomological News, Vol. 15, Jan., 1904. 
Records of three species, their breeding-places, habits, etc. 

Mitchell, Evelyn G. Mosquito Life. N. Y., 1907. A good 
popular account of the mosquitoes and their relation to disease. 
The appendix treats of mosquitoes and their possible relation 
to leprosy. 

Smith, J. B. Mosquitoes Occurring Within the State of New 
Jersey. Report of the New Jersey State Agric. Exper. Station 
upon the mosquitoes occurring within the State. Trenton, 
N. J., 1904. Habits, development, relation to disease, checks 
and remedies; systematic. 

Smith, J. B. The General Economic Importance of Mosquitoes. 
Popular Science Monthly, 70, 1907, pp. 325-329. Mosquitoes 
affect not only the health and comfort of the people, but 
hinder development of agriculture and thus affect land 
values. 

Smith, J. B. The New Jersey Salt-marsh and Its Improve- 
ment. New Jersey Agricultural Experiment Station Bulletin, 
207, 1907. Shows that the increased value of the land drained 
in the antimosquito crusade more than pays for the cost of the 
drainage. 

Theobald, F. V. Monograph of Culicidce of the World. Four 
Vols, and one Vol. of plates. London, 1901 to 1907. Vol. I 
contains 96 pages on structure, life-history, habits, etc. Vol. II 
contains a bibliography. Vol. Ill contains a list of species 
that carry disease. 

Theobald, F. V. Mosquitoes or Culicidce. In Albutt and Rol- 
leston's System of Medicine, II, 1907, pp. 122-168. Structure, 
life-history, habits, distribution and classification of mosqui- 
toes. Bibliography. 



1 82 Insects and Disease 



MOSQUITO ANATOMY 

Berkeley, Wm. M. Laboratory Work with Mosquitoes. N. Y., 
1902. Chapters on development, anatomy, dissection, malarial 
parasites, filarial disease, yellow fever. 

Dimmock, Geo. Anatomy of the Mouth-parts and Suctorial 
Apparatus of Culex. Psyche, 3, pp. 231-241, Sept., 1881. 
Good. 

Imms, A. D. On the Larval and Pupal Stages of Anopheles 
maculipennis. Journal Hygiene, Vol. 7, No. 2, April, 1907. 
Morphology. 

Imms, A. D. On the Larval and Pupal Stages of Anopheles 
maculipennis. Parasitology, Vol. I, No. 2, June, 1908. Con- 
tinuation of article in Jour. Hyg., Vol. 7, No. 2. Continues 
discussion of morphology. 

Nuttall, Geo. F., Corbett, Louis, and Strangeways-Pig, 
T. Studies in Relation to Malaria. Pt. I, The Geographical 
Distribution of Anopheles in Relation to the Former Distribu- 
tion of Ague in England. Jour. Hyg., Vol. I, No. 1, Jan., 1901. 

Nuttall, Geo. F., and Shipley, Arthur E. Studies in Rela- 
tion to Malaria. Pt. II, Structure and Biology of Anopheles, 
Jour Hyg., Vol. I, No. 1, Jan., 1901: The Egg and Larva; 
Bibliography. Pt. II, cont., Vol. I, No. 2, April, 1901: The 
Pupa. Pt. II, cont., Vol. I, No. 4, Oct., 1901: Adult External 
Anatomy. Pt. II, cont., Vol. 2, No. 1, Jan., 1902: ^Etiology 
of Adult. Pt. II, cont., Vol. Ill, No. 2, April, 1903: Anatomy 
of Adult. 

Thompson, Millett T. Alimentary Canal of the Mosquito. 
Proc. Bost. Soc. Nat. Hist., Vol. 32, No. 6, 1905, pp. 145-202. 
Good summary of recent investigations. 

Wesche, W. The Mouth-parts of Nemocera and Their Rela- 
tion to the Other Families of Diptera. Royal Microscopic Soc. 
Jour., 1904, pp. 28-47. Discussion with illustrations of the 
mouth-parts of various Diptera. 



Bibliography 183 



MOSQUITOES— LIFE-HISTORY AND HABITS 

Ayers, E. A. The Secrets of the Mosquito. A guide to the 
extermination of the prolific pest. World's Work, 1907, 
Vol. 14, pp. 8902-8910. Notes on life-history and methods 
of control. 

Jordan, E. O., and Hefferan, Mary. Observations on the 
Bionomics of Anopheles. Jour. Infec. Diseases, II, 1905, pp. 56- 
69. Occurrence, breeding-places, habits, etc. 

Morgan, H. A., and Dupree, J. W. Development and Hiberna- 
tion of Mosquitoes. Bull. 40, N. S., Div. of Ento., pp. 88-92, 
1903. Results of observation on five genera of mosquitoes in 
the vicinity of Baton Rouge, La. 

Ross, E. H. The Influence of Certain Biological Factors on 
the Question of the Migration of Mosquitoes. Jour. Trop. 
Med. 6° Hyg., 12, 1909, pp. 256-258, Sept. 1. Only fecun- 
dated females feed on blood, and must be fertilized after each 
batch of eggs. This determines largely the time and place of 
breeding. 

Smith, J. B. Concerning Migration of Mosquitoes. Science, 18, 
Dec. 11, 1903, pp. 761-764. Observations on the migrations 
of mosquitoes, particularly C. sollicitans. 

MOSQUITO FIGHTING 

Celli, Angelo. The Campaign Against Malaria in Italy. 
Transl. by J. J. Eyre. Jour. Trop. Med. & Hyg., XI, Apr. 1, 
1908, pp. 101-108. Includes a good discussion of the effective- 
ness of destroying the mosquitoes in controlling malaria. 

Felt, E. P. Mosquito Control. In Report of the N. Y. State 
Entomologist for 1905, pp. 109-116. Notes on importance and 
methods of control of various species. 

Goldberger, Jos. Prevention and Destruction of Mosquitoes. 
Public Health Reports, Pub. Health and Mar. Hospt. Ser. t 



184 Insects and Disease 

July 17, 1908. Life-histories and methods of fighting lame, 
pupae and adults. 

Le Prince, J. A. Mosquito Destruction in the Tropics. Jour. 
Amer. Med. Assn., LI, p. 26, Dec. 26, 1908. Occurrence 
and habits of Anopheles, methods of destruction. Results of 
anti-malarial work on the isthmus. Discussion by various 
doctors. 

Quayle, H. J. Mosquito Control Work in California. Bull. 
No. 178, Calif. Agric. Ex. Sta., pp. 1-55, 1906. Habits and 
life-history of California species, with an account of experi- 
ments to control the salt-marsh species. 

Rosenan, M. J. Disinfection Against Mosquitoes with For- 
maldehyde and Sulphur Dioxid. Hyg. Lab. Pub. Health and 
Mar. HospL Ser., Bull. 6, 1901. 

Ross, Ronald. Mosquito Brigades and How to Organize Them. 
New York, 1902. 

Ross, Ronald. Logical Basis of the Sanitary Policy of Mosquito 
Reduction. Science, N. S., Vol. 22, No. 750, Dec. 1, 1905, 
pp. 689-699. Important article dealing with the methods of 
control. 

Smith, J. B. Salt-marsh Mosquitoes. New Jersey Agric. 
Exper. Stn. Special Bulletin T, 1902. Breeding-places and 
methods of control of this species. 

Smith, J. B. Mosquitocides. Bull. 40, New Series U. S. Dept. 
Agric, Div. of Ento., pp. 96-108, 1903. Results of experi- 
ments with a number of substances, several of which were 
found to be effective and some cheap enough to permit of 
their use to a limited extent. 

Smith, J. B. The New Jersey Salt-marsh and Its Improve- 
ment. Bull. No. 207, Nov. 14, 1907, New Jersey Agric. 
Exper. Stn. Results of draining the marshes to get rid of 
mosquitoes. 

Smith, J. B. The House Mosquito: a City, Town and Village 
Problem. N. J. Agric. Ex. Stn. Bull. 216, 1908. Work done 



Bibliography 185 

on salt-marshes since 1904 practically eliminated the migratory 
species, so that C. pipens, the house mosquito, is now the 
problem. Life-history and methods of combating. 

Underwood, W. L. Mosquitoes and Suggestions for Their 
Extermination. Pop. Sci. Mo., Vol. 63, 1903, pp. 453-466. 
Life-history, habits and methods of control. 

Underwood, W. L. The Mosquito Nuisance and How to 
Deal with It. Boston, 1903. 

First Antimosquito Convention, 1903. Pub., Brooklyn, 1904. 
Contains articles on what railroads, government and laws 
should do toward mosquito extermination; mosquito work in 
Havana; how state appropriations should be used, etc. 

National Mosquito Extermination Society. Bulletin No. 1, 
1904. Object of Society; brief sketches of Ross, Reed, and 
others. Reprints of a few articles on mosquito extermination. 

American Mosquito Extermination Society. Year Book for 
1904-05. N. Y., 1906. Containing reports of meetings and 
discussions of various problems. Several interesting papers, 
among them " Criminal Indictment of the Mosquito," F. W. 
Moss. " Mosquito Work at Panama Canal," W. C. Sorgas. 
" Diversities Among New York Mosquitoes," E. P. Felt. 
" Mosquito Extermination in New Jersey," J. B. Smith. 
" The Mosquito Question," Quitman Kohnke. 

Antimalarial Work in the Panama Canal Zone. Editorial in 
Jour. Trop. Med. & Hyg., XI, Aug. 15, 1908, p. 251. Notes 
on the success of the measures adopted there. 

MOSQUITOES AND DISEASE 

Doty, A. H. The Mosquito, Its Relation to Disease and Its 
Extermination. New York State Journal of Medicine, May, 
1908. 

Finlay, Chas. Mosquitoes Considered as Transmitters of 
Yellow Fever and Malaria. Med. Record, May 27, 1899, 



1 86 Insects and Disease 

pp. 737-739. Review of his theory in regard to mosquitoes 
and disease and the probable necessary changes in view of 
recent discoveries. 

Howard, L. O. Mosquitoes as Transmitters of Disease. Re- 
view 0} Reviews, XXIV, 1901, pp. 192-195. A review of the 
work of various investigators. 

Smith, J. B. Sanitary Aspect of the Mosquito Question. Medi- 
cal News, Mar. 7, 1903. Note on mosquitoes and their rela- 
tion to disease. 

Taylor, J. B. Observations on the Mosquitoes of Havana, 
Cuba. Reprint from La Revista de Medicina, June, 1903, p. 27. 

MALARIA 

Banks, C. S. Experiments in Malarial Transmission by Means 
of Myzomyia ludlowii. Phil. Jour. Sci., B. 2, 1907, pp. 513- 
535. Breeding-places of mosquitoes, life-histories of the spe- 
cies; mosquitoes and malaria. 

Craig, C. F. Malarial Fevers. Osier's Mod. Med., Vol. I, p. 392, 
1907. Historical ; distribution ; malarial parasites ; classification ; 
development; malarial mosquitoes; pathology; treatment, etc. 

Craig, C. F. Studies in the Morphology of Malarial Plasmodia 
after the Administration of Quinine and in Intracorpuscular 
Conjugation. Jour. Infec. Diseases, VII, No. 2, 1910. See 
also same, IV, 1907, pp. 108-140. Gives the evidence upon 
which he bases his theory of the meaning of intracorpuscular 
conjunction. 

Craig, C. F. The Malarial Fevers, Hemoglobinuric Fever and 
the Blood Protozoa of Man. N. Y., 1909. A thorough con- 
sideration of the subject of malaria and good discussion of 
the other subjects noted in title. Bibliography. 

Deaderick, W. H. Malaria. Philad., 1909. The chapter on 
aetiology treats of the transmission by mosquitoes. 

Harris, S. Prevention of Malaria. Jour. Amer. Med. Assn., 53, 



Bibliography 187 

Oct. 9, 1909, pp. 1162-67. Effects of malaria, transmission 
by mosquitoes, etc. In the discussion of the paper J. H. White 
summarizes the fight against yellow fever in New Orleans. 

Herrick, G. W. Relation of Malaria to Agriculture and Other 
Industries of the South. Economic losses occasioned by 
malaria; malaria responsible for more sickness among the 
white population than any other disease; relation to mosqui- 
toes. Pop. Sci. Mo., Vol. 62, Apr., 1903, pp. 521-525. 

Jones, Ross, Ellett. Malaria. London, 1907. Small book, 
introduction by Ross. Malaria in Greece and Italy; shows 
how this disease contributed to the downfall of great nations. 

Mannaberg, Julius. Malaria. In Nothnagel's Encyclopedia 
of Practical Med., Amer. Ed., 1905, pp. 17-494. A very com- 
prehensive discussion of the disease and the relation of mos- 
quitoes to the malarial parasite. 

Manson, Patrick. The Mosquito and the Malaria Parasite. 
Brit. Med. Jour., Vol. II for 1898, pp. 849-853. History of 
the parasite in the human and insect host; observations of 
Ross and others and their meaning. 

Manson, Patrick. Experimental Demonstration of the Mos- 
quito-malarial Theory. Brit. Med. Jour., Vol. 2 for 1900, 
pp. 949-951, also Lancet, II, 1900, pp. 923-925. Infected 
mosquitoes sent from Rome allowed to bite men in England 
who had not been in malarial regions. Malarial fever 
followed. 

Manson, Patrick. Malarial Fever. Appendix to Vol. IX of 
T. C. Albutt's System of Med., 1900. Relation of the malarial 
parasite to the disease and to mosquitoes. 

Robertson, E. W. Renaming of Malaria— Anophelesis. Va. 
Medical Semi-monthly, Sept. 10, 1909. Considers malaria a 
misnomer and gives reasons for suggesting new name. 

Ross, Ronald. On Some Peculiar Pigmented Cells Found in 
Two Mosquitoes Fed on Malarial Blood. Brit. Med. Jour. f 
1897, Dec. 18, p. 1786. Records in his experiments in feeding 



1 88 Insects and Disease 

mosquitoes on blood of malarial patients. Records finding the 

parasites in some of them. Important article. 
Ross, Ronald. Pigmented Cells in Mosquitoes. Brit. Med. 

Jour. j 1898, Feb. 26, p. 550. Further notes on them. 
Ross, Ronald. The Mosquito Theory of Malaria. Report 

dated Calcutta, Feb. 16, 1899. Reprinted in Pop. Sci. Monthly, 

Vol. 56, Nov., 1899, PP- 42-46. Tells of his investigations in 

India and their results. 
Ross, Ronald. The Relationship of Malaria and the Mosquito. 

Lancet, II, 1900, July 7, p. 4880. Observation on the trans- 
mission of malaria. 
Ross, Ronald. Malaria Fever, Its Cause, Prevention and 

Treatment. London, 1902. Chapters on malaria, mosquitoes, 

prevention and treatment. 
Ross, Ronald. Parasites of Mosquitoes. Jour, of Hyg., VI, 

No. 2, Apr., 1906. Brief review of several of his earlier papers 

on this subject with additional notes. 
Simpson, W. J. R. Recent Discoveries Which Have Rendered 

Antimalarial Sanitation More Precise and Less Costly, Brit. 

Med. Jour. , 1907, II, pp. 1044-46. Discussion of the various 

factors in mosquito control. 
Stephens, J. W. W., and Christophers, S. R. The Practical 

Study of Malaria and Other Blood Parasites. London, 1908. 

Chapters on mosquitoes, flies and ticks and their relation to 

diseases. 
Sternberg, G. M. The Malarial Parasite and Other Patho- 
genic Protozoa. Pop. Sci. Mo., Vol. 50, 1897, pp. 628-641. 

Account of the discovery of the malarial parasite and more 

recent studies on it. 
Sternberg, G. M. Malaria. Smith. Rept., 1900, pp. 645-656. 

Review of the experimental evidence in support of the mosquito- 
malaria theory. 
Malarial Fever. Jour. Trop. Med. & Hyg., II, Mar. 16, 1908, 

pp. 96-98. A list of literature mostly for the years 1906 and 1907. 



Bibliography 189 

YELLOW FEVER 

Adams, S. H. Yellow Fever, a Problem Solved. The battle of 
New Orleans against the mosquito. McClure's Magazine, 
Vol. 27, June, 1906, p. 178. An interesting popular article. 

Carroll, James. Yellow Fever. Osier's Mod. Med., Vol. II, 
1907, p. 736. History, aetiology, treatment. A good review of 
the work of the Yellow Fever Com. and the results of their work. 

Carroll, James. The Transmission of Yellow Fever. Amer. 
Med. Assn., 40, 1905, pp. 1429-33. Shows the relation of the 
mosquito to the disease. 

Carroll, James. Yellow Fever. Lessons to be learned from 
the present outbreak of yellow fever. Jour, of Amer. Med. 
Assn., Vol. 45, 1905, pp. 1079-81. Among other things rec- 
ommends that mosquitoes be kept from patients. 

Chaille, S. E. The Stegomyia and Fomites. Amer. Med. 
Assn., 40, 1903, pp. 1433-40. Concludes that the mosquito is 
the only proven disseminator of yellow fever. Extended dis- 
cussion by various physicians. 

Dastre, A. The Fight Against Yellow Fever. Smith. Rept., 
1905, pp. 339-350. History of the yellow fever epidemics, its 
geographical distribution, and the work that is being done to 
control it. 

Doty, A. H. On the Mode of Transmission of the Infectious 
Agent in Yellow Fever and Its Bearing upon the Quarantine 
Regulations. Med. Record, Oct. 26, 1901, pp. 649-653. Re- 
view of older theories in regard to the spread of yellow fever. 
Believes that the quarantines are now unnecessary. 

Finley, Chas. The Mosquito Theory of the Transmission of 
Yellow Fever and Its New Development. Med. Record, 
Jan. 19, 1901. Refers to his early observations on the subject, 
giving extracts from some of his earlier papers to show that 
he had long held the mosquito responsible for the dissemina- 
tion of yellow fever. 



190 Insects and Disease 

Goldberger, Jos. Yellow Fever, ^Etiology, Symptoms and 
Diagnosis. Yellow Fever Inst. Bull. 16, Pub. Health and 
Mar. Hospt. Ser., 1907. Includes discussion of the relation 
of mosquitoes to the disease. 

Guiteras, John. Experimental Yellow Fever at the Inocula- 
tion Station of the Sanitary Department of Havana. Amer. 
Med., Vol. II, No. 21, 1901, pp. 809-817. Experiments show 
that all types of the yellow fever from mild to severe may be 
produced by the bite of the mosquito. 

McFarland, Joseph. Life and Work of James Carroll. Mem- 
oir read at the fifth annual meeting of the Soc. of Tropical 
Med., 1908. Early life of Carroll and his work with the Yellow 
Fever Com. 

Parker, H. B., Beyer, G. E., and Pothier, O. L. Rept. of 
Working Party No. 1, Yellow Fever Institute. Bull. 13, Pub. 
Health and Mar. Hospt. Ser., 1903. As a result of their studies 
they believe that the disease is caused by a protozoan parasite 
which they name and describe. Discuss the relation of mos- 
quitoes to the disease. 

Reed, Walter; Carroll, James; and Agramonte, A. Experi- 
mental Yellow Fever. Amer. Med., July 6, 1901, pp. 15-23. 
Records of certain experiments and their results. 

Reed, Walter; Carroll, James; and Agramonte, C. A. The 
^Etiology of Yellow Fever. A preliminary note presented at the 
Amer. Pub. Health Assn. Philad. Med. Jour., Oct. 27, 1900, pp. 
790-796. Also an additional note in Jour. Amer. Med. Assn., 36, 
pp. 431-440, 1901. Records of their experiments and a sum- 
ming up of the data in regard to yellow fever and the mosquito. 

Reed, Walter, and Carroll, James. The Prevention of 
Yellow Fever. Med. Record, Oct. 26, 1901, pp. 441-449. 
History of the disease, especially in U. S., results of the work 
of Yellow Fever Com. description, life-history and habits of 
the mosquito, its relation to yellow fever, methods of control. 
Important paper. 



Bibliography 191 

Reed, Walter. Recent Researches Concerning the ^Etiology, 
Propagation and Prevention of Yellow Fever by U. S. Army 
Com. Jour. Hyg., 2, 1902, pp. 101-119. Review of work 
of the Yellow Fever Com. and the importance of the results. 
Bibliography. 

Rosenan, M. J., Parker, H. B., Francis, E., and Beyer, G. E. 
Rept. of Working Party No. 2, Yellow Fever Institute. Ex- 
perimental studies in yellow fever and malaria at Vera Cruz, 
Mex. U. S. Pub. Health and Mar. Hospt. Ser., May, 1904. 
Includes experiments and observations on mosquitoes. 

Rosenan, M. J., and Goldberger, Jos. Report of Working 
Party No. 3, Yellow Fever Institute. Yellow Fever Inst. 
Bull. 15, Pub. Health and Mar. Hospt. Ser., 1906. Unsuc- 
cessful attempts to grow the yellow fever parasite. Negative 
results in the experimental study of the hereditary transmis- 
sion of the yellow fever in the mosquito. Appendix A gives a 
translation of Marchoux and Simonds' report in which they 
report positive results in their experiments alone the same line. 

Sternberg, G. M. Transmission of Yellow Fever by Mos- 
quitoes. Smith. Rept., 1900, pp. 657-673. Review of the early 
theories in regard to yellow fever and the work and findings of 
the yellow fever commission. 

White, J. H. Yellow Fever and the Mosquito. Jour. Amer. 
Med. Assn., LI, No. 26, Dec. 26, 1908. Considers both S. 
calopus and C. pungens. Results of early mistakes. Neces- 
sity of destroying mosquito. Methods of destroying mosquito. 
Habits of mosquito. 

Abstract of the Report of the French Yellow Fever Com. at 
Rio de Janeiro, 1903. Pub. Health Report, Pub. Health and 
Mar. Hospt. Ser., Vol. 19, Pt. I, p. 1019. A summary of their 
findings and conclusions to the date of report. 

DE Ybarra, A. M. F. Yellow Fever Again in Cuba. Jour. 
Trop. Med. &• Hyg., XI, Mar. 2, 1908, pp. 73-78. Cites a 
number of cases of yellow fever within the last few years and 



192 Insects and Disease 

uses them as evidence to show that the disease may be trans- 
mitted in other ways than by the mosquito. A strong summing 
up of the arguments against the mosquito theory. Reprint of 
editorial in Tex. Med. Jour., Oct., 1907, also follows this 
article. 

The Extinction of Yellow Fever at Rio de Janeiro. Lancet, II, 
1909, p. 404. A review of a French publication giving the re- 
sults of the work from 1903 to present time. In 1903 before 
work was begun there were 584 deaths from yellow fever. In 
1908 only 4, and none so far in 1909. Success accredited to 
mosquito work and general sanitation. 

A Pioneer in Research on Yellow Fever. Editorial in Brit. Med. 
Jour., May 30, 1908, p. 1306. Refers to the work of L. D. 
Beauperthuy, who, in 1853, set forth the theory that yellow 
fever was transmitted by mosquitoes. 

DENGUE 

Ashburn, P. M., and Craig, C. F. Experimental Investiga- 
tions Regarding the ^Etiology of Dengue Fever. Jour. Injec. 
Diseases, Vol. V, 1907, pp. 440-475. Conclude that the 
disease is spread only by mosquitoes. 

Coleman, Thomas D. Dengue. Osler J s Mod. Med., Vol. II, 
1907, p. 489. ^Etiology, pathology, etc.; possibility of Culex 
fatigans disseminating the disease. 

Graham, H. "The Dengue"; a Study of Its Pathology and 
Mode of Propagation. Jour, of Trop. Med. &° Hyg., July 1, 
1903, p. 209. Experiments which seem to show that dengue 
is transmitted by Culex fatigans. 

Leichtenstern, O. Dengue. In Nothnagel's Encyclopedia of 
Practical Med., Amer. Ed., 1905, pp. 720-743. Consideration 
of the disease and its transmission. 

Ross, E. H. The Prevention of Dengue Fever. Amer. Trop. 
Med. cV Parasit., Vol. II, No. 3, July 1, 1908, pp. 193-195. 



Bibliography 193 

A successful campaign against the mosquitoes in Port Said in 
1906 stopped the outbreaks of malaria and dengue. 
Dengue and Sand-flies. Jour. Trop. Med. 6° Hyg., 12, 1909, 
pp. 172-173. A note on these pages refers to the work of Dr. 
R. Doerr, who suspects that dengue may be carried by sand- 
flies, Phlobotomus, as well as by mosquitoes. 

FILARIAL DISEASES AND ELEPHANTIASIS 

Christophers, S. R. What Is Really Known of the Cause of 
Elephantiasis. Ind. Med. Gaz., Nov., 1907, p. 404. Ques- 
tions Manson's theory in regard to the disease being caused by 
filaria. 

Manson, Patrick. Tropical Diseases. London, 1908, pp. 594- 
648. A most comprehensive chapter on filariasis and ele- 
phantiasis. 

Phalen, J. M., and Nichols, H. J. Filariasis and Elephantiasis 
in Southern Luzon. Phil. Jour. Sci., Sept., 1908. Culex 
microannulatus regarded as the carrier of the filaria. 

Prout, W. T. On the Role of Filaria in the Production of 
Disease. Jour. Trop. Med. 6° Hyg., Apr. 1, 1908, p. 109. 
Discussion of same in same journal, June 1, 1908. 

White, Duncan. Filarial Periodicity and Its Association with 
Eosinophilia. Jour. Trop. Med. & Hyg., 12, July 15, 1909, 
pp. 175-183. Among other things he discusses the relation of 
mosquitoes to filarial diseases. 

LEPROSY 

Brinckerhoff, W. R. A Note upon the Possibility of the 
Mosquito Acting in the Transmission of Leprosy. Pub. 
Health and Mar. Hospt. Ser. (general publications), 1908. 
Suggests the possibilities of such transmission, but concludes 
that the probabilities are against it. 



194 Insects and Disease 

Goodhue, E. S. The Bacillus Leprae in the Gnat and Bedbug. 

Ind. Med. Gaz., Vol. XLI, Aug., 1906, p. 342. Has found this 

bacillus in mosquitoes and bedbugs, but believes the latter is 

more concerned in transmitting the disease. 
Goodhue, E. S. Mosquitoes and Their Relation to Leprosy in 

Hawaii. Amer. Med., N. S., 2, 1907, p. 593. Suggests that 

mosquitoes may carry the disease, also warns against danger 

from flies and bedbugs. 
Hutchinson, J. Mosquitoes and Leprosy. Brit. Med. Jour., 

Dec. 22, 1906, Vol. II, p. 1841. Evidence against the insect 

theory of transmission of leprosy. 
Mugliston, T. C. On a Possible Mode of Communication of 

Leprosy. Jour. Trop. Med., Vol. VIII, July 15, 1905, p. 209. 

Suggests that the itch-mite may be the carrier of leprosy. 

Studies on 77 lepers led him to this conclusion. 
Smyth, W. R. Leprosy. Brit. Med. Jour., Dec. 8, 1906, Vol. II, 

p. 1670. Believes that bedbugs or some similar wingless 

parasite conveys the disease. 

PLAGUE 

Brannerman, W. B. Spread of Plague in India. Jour. 0} Hyg., 
Vol. 6, No. 2, Apr., 1906, pp. 179-21 1. A digest of experi- 
ments made in India. Discusses various ways in which the 
disease may be spread. Review of the evidence that insects 
may be concerned. Bibliography. 

Calvert, W. J. Plague. Osier's Mod. Med., Vol. II, 1907, 
p. 760. History; bacteriology; pathology; plague among ani- 
mals; transmission, etc. 

Ham, B. Burnett. Report on Plague in Queensland, 1900-1907. 
P. 153 discusses the rat-flea theory of dissemination of bubonic 
plague, summing up the evidence of various observers, includ- 
ing the Indian Advisory Com. and others. Considers the evi- 
dence conclusive that P. cheopis and possibly C. jasciatus 



Bibliography 195 

transmit plague. Other pages discuss various rat fleas and 
their relation to plague in rats. 

Hankin, E. H. On the Epidemiology of Plague. Jour. Hyg., 5, 
1905, pp. 48-83. A comprehensive discussion of the disease 
and its spread, several pages devoted to rats and fleas; evi- 
dence for and against the theory that rats and fleas are the 
principal carriers of the disease. 

Herzog, Max. The Plague, Bacteriology, Morbid Anatomy & 
Histopathology, Including the Consideration of Insects as 
Plague Carriers. Biological Laboratory Bureau of Govt. 
Laboratories, Manila, Oct., 1904. Reviews the evidence 
regarding the possibility of fleas carrying plague; describes a 
new rat flea (Pulex philippinensis); records experiments with 
fleas and cites a case of bubonic plague in a child in which the 
infection was possibly carried by Pediculi. 

McCoy, G. W. Plague Bacilli in Ectoparasites of Squirrels. 
Pub. Health Reports, Pub. Health and Mar. Hospt. Ser., 
Vol. XXIV, No. 16, Apr. 16, 1909. Experiments with fleas 
and lice from infected squirrels demonstrating presence of 
plague bacilli. 

McCoy, G. W. The Susceptibility of Gophers, Field-mice and 
Ground-squirrels to Plague Infection. Jour, of Infec. Diseases, 
Vol. 6, 1909, No. 3, pp. 283-288. Gophers highly resistant, 
field-mice moderately susceptible and ground-squirrels very 
susceptible to plague. 

Mitzmain, M. B. Insect Transmission of Bubonic Plague: a 
Study of the San Francisco Epidemic. Ento. News, 19, 
No. 8, 1908, pp. 353-359. Fleas obtained in examination of 
1,800 rats. Attempt to locate source of rat and flea introduc- 
tion. 

Morton, F. M. Eradicating Plague from San Francisco. Re- 
port of the Citizens' Health Com. and an account of its work. 
San Francisco, 1909. Discusses the epidemics, methods of 
transmission, methods of fighting, etc. 



196 Insects and Disease 

Rucker, W. C. Plague Among Ground-squirrels in Contra 
Costa Co., Cal. Pub. Health Reports, Pub. Health and Mar. 
Hospt. Ser., Aug. 27, 1909. Reports of human cases supposed 
to be connected with plague among ground-squirrels. Plague 
among squirrels; habits, methods of fighting, etc. 

Rucker, W. C. Fighting an Unseen Foe. Sunset Mag., XXII, 
No. 2, Feb., 1909. Story of the fight against plague in San 
Francisco. 

Shipley, A. E. Rats and Their Animal Parasites. Jour. Eco. 
Biology, Vol. Ill, No. 3, Oct. 28, 1908. List of species of ecto- 
and endoparasites. 

Simpson, W. J. A Treatise on Plague. Cambridge Univ. Press, 
London, 1906. Deals with historical, epidemiological, clinical, 
therapeutic and preventive aspect of the disease. 

Thompson, J. A. The Mode of Spread and Prevention of 
Plague in Australia. Lancet, Oct. 19, 1907, p. 1104. Rat 
fleas the essential factor in transmitting plague, and preventive 
methods should be directed against the rats. 

Thompson, J. A. On the Epidemiology of Plague. Jour. Hyg., 
Vol. VI, No. 5, Oct., 1906. Methods of infection, spread, 
relation of rats to the disease and a review of the rat -flea 
theory. Bibliography. 

Verjbitski, D. T. The Part Played by Insects in the Epi- 
demiology of Plague. Jour. Hyg., 8, 1908, No. 2, pp. 
162-208. Record of extensive experiments with fleas. Fleas 
communicated plague for three days, bedbugs for five days. 
Interrelation of fleas, rats, dogs, cats, and man. An important 
article translated from Russian. 

Wherry, W. B. Further Notes on the Rat Leprosy and on the 
Fate of the Human and Rat Leper Bacillus in Flies. Jour. 
Injec. Diseases, Vol. 5, No. 5, 1908. Discussion and references, 
experiments with flies, summary, etc. More than 1,115 lepra - 
like bacilli were counted in a single fly-speck. 

Wherry, W. B. Plague Among the Ground-squirrels of Cali- 



Bibliography 197 

fornia. Jour. Infec. Diseases, Vol. 5, No. 5, 1908, pp. 485-533- 
How the plague was first discovered among rats, records of 
cases and a discussion of the possible relation of this to human 
plague cases. 

Eradicating Plague in San Francisco; Report of the Citizens' 
Health Committee, 1909. An account of the recent outbreaks 
and the methods of fighting them. 

Report of the Indian Plague Commission, Vol. V, pp. 75-77, 
1901. In these pages the Commission considers the question 
of the transference of plague by suctorial insects. It con- 
siders Simonds' claims and others and believes that "suctorial 
insects do not come under consideration with the spread of 
plague." 

Reports on Plague Investigations in India Issued by the Ad- 
visory Committee Appointed by the Sec. of State for India, 
the Royal Society and the Lister Institute. The reports in- 
clude the reports of the Working Commission appointed by 
the Advisory Committee and reports on various contributory 
investigations. They are published in the Jour, of Hygiene 
as "Extra Plague Numbers." All these reports deal very 
largely with the relation of the rat and flea to plague, and are 
commonly referred to as "Reports of Indian Plague Commis- 
sion." The first number, Vol. VI, Sept., 1906, contains 
articles on "Experiments upon the Transmission of Plague 
by Fleas." "Note on the Species of Fleas Found on Rats, 
Mus rattus and Mus decumanus in Different Parts of the 
World." "The Physiological Anatomy of the Mouth-parts 
and Alimentary Canal of the Indian Rat Flea, Pulex cheopis," 
and other papers on the relation of rats to plague. The second 
number, Vol. VII, July, 1907, contains articles on "On the 
Significance of the Locality of the Primary Bubo in Animals 
Infected with Plague in Nature," "Further Observations on 
the Transmission of Plague by Fleas with Special Reference 
to the Fate of Plague Bacillus in the Body of the Rat Flea," 



198 Insects and Disease 

"Experimental Production of Plague Epidemics Among Ani- 
mals," "Experiments in Plague Houses in Bombay," "On 
the External Anatomy of the Indian Rat Flea and Its Differ- 
entiation from Some Other Common Fleas," "A Note on 
Man as a Host of the Indian Rat Flea," and others on the 
relation of rats to plague. The third number, Vol. VII, 
Dec, 1907, contains articles on "Digest of Recent Observa- 
tions on the Epidemiology of Plague" (Bibliography), "Epi- 
demiological Observations in Bombay City," "Epidemiological 
Observations in the Villages of Wadhala, Parel, Worli in 
the Neighborhood of Bombay Village," "General Considera- 
tions Regarding the Spread of Infection, Infectivity of Houses, 
etc., in Bombay City and Island," "Epidemiological Observa- 
tions in the villages of Dhand and Kasel (Punjab)." The 
fourth number, Vol. VIII, May, 1908, contains articles on "The 
Part Played by Insects in the Epidemiology of Plague" (see 
also ref. under D. T. Verjbitski). "Observations on the Bio- 
nomics of Fleas with Special Reference to P. cheopis" "The 
Mechanism by Means of Which the Flea Cleans Itself of 
Plague Bacilli," "On the Seasonal Prevalence of Plague in 
India." 
See also under Fleas. 

FLEAS 

Baker, C. F. Fleas and Disease. Science, N. S., Vol. 22, 
No. 559, Sept. 15, 1905, p. 340. Discusses the possibility of 
fleas transmitting leprosy. 

Doane, R. W. Notes on Fleas, Collected on Rat and Human 
Hosts in San Francisco and Elsewhere. Can. Ento., 40, 1908, 
pp. 303-304. Shows that Ceralophyllus fasciatus and Pulex 
irritans are common on both man and rats. 

Fox, Carroll. The Flea in Its Relation to Plague, with a 
Synopsis of the Rat Fleas. The Military Surgeon, 24, June, 
1909, pp. 528-537. Review of the work of the Indian 



Bibliography 199 

Plague Commission and others. Key for identification of rat 
fleas. 

Galli-Valerio. The Part Played by Fleas of Rats and Mice 
in the Transmission of Bubonic Plague. Jour. Trop. Med., 
Feb., 1902. Attacks the theory that plague can be conveyed 
from rats to men by fleas because rat fleas do not bite men. 

McCoy, G. W. Siphonaptera Observed in the Plague Cam- 
paign in California with a Note upon Host Transference. 
Pub. Health Report, Pub. Health and Mar. Hospt. Ser., 
Vol. XXIV, No. 29, July 16, 1909. Lists of species from 
various hosts. Report on experiments in transferring rat 
fleas to squirrels and squirrel fleas to rats. 

McCoy, G. W., and Mitzmain, M. B. An Experimental In- 
vestigation of the Biting of Man by Fleas Taken from Rats 
and Squirrels. Public Health Report, XXIV, No. 8, Feb. 19, 
1909, pp. 189-194, Rat and squirrel fleas will bite man. 

Mitzmain, M. B. Insect Transmission of Bubonic Plague. A 
Study of the San Francisco Epidemic. Entomological News, 
Oct., 1908. Source and distribution of species of fleas and 
brief notes on work of Indian Plague Commission. 

Mitzmain, M. B. How a Hungry Flea Feeds. Entomological 
News, Dec, 1908. 

Mitzmain, M. B. Some New Facts on the Bionomics of the 
California Rodent Fleas. Annals Ento. Soc. Amer., Ill, pp. 61- 
82, 1910. 

Shipley, A. E. Rats and Their Animal Parasites. Jour, of 
Economic Biology, Vol. 3, No. 3, Oct. 28, 1908. List of species 
ecto- and endoparasites. 

See also reports of Advisory Commission under Plague. 

TYPHOID FEVER 

Anderson, J. F. The Differentiation of Outbreaks of Typhoid 
Fever Due to Water, Milk, Flies and Contact. Amer. Jour. 
Pub. Health, 19, pp. 251-259. Discusses flies and typhoid. 



200 Insects and Disease 

McCrea, Thomas. Typhoid Fever. Osier's Mod. Med., 
Vol. II, p. 70, 1907. A full discussion of this disease. 

Reed, Walter; Vaughan, V. C, and Shakespeare, E. O. 
Abstract of Report on the Origin and Spread of Typhoid 
Fever in the U. S. Military Camps During the Spanish War 
of 1898. Washington, Govt. Printing Office, 1900. Shows 
among other things that "flies undoubtedly served as carriers 
of infection." 

Roseman, M. J., Lumsden, L. L., and Kastle, J. H. Report 
on Origin and Prevalence of Typhoid Fever in D. C. Including 
reports by Stiles, Goldberger and Stimson. Bull. 35 0} Hygienic 
Laboratory of U. S. Public Health and Mar. Hospt. Ser., 1907. 
(Second report in Bull. 44, 1907, includes nothing about insects.) 

Veeder, M. A. Typhoid Fever from Sources Other Than 
Water Supply. Med. Record, 62, pp. 1 21-124, J u ty 2 6, 1902. 
Cites several instances where flies might act as the carriers of 
the disease. 

Whipple, Geo. C. Typhoid Fever, Its Causation, Transmission 
and Prevention. N. Y., 1908. Considers that house-flies and 
probably fruit-flies carry typhoid bacilli. 

HOUSE-FLIES; ANATOMY, LIFE-HISTORY, HABITS 

Felt, E. P. Observations on the House-fly. Jour. Eco. Ento., 

Ill, No. 1, Feb., 1910, pp. 24-26. Shows that it does not breed 

freely in darkness. 
Griffith, A. The Life-history of House-flies. Public Health 

(London), 21, No. 3, 1908, pp. 122-127. Study of life-history. 

Flies require water frequently, eggs hatch in twenty-four hours, 

larval stage four days. Each female may lay four batches of 

eggs. Destroy manure and rubbish. 
Hamer, W. H. The Breeding of Flies Summarized. Am. Med., 

3, 1908, p. 431. Habits of flies and experiments to show that 

they may carry the germs of various diseases. 



Bibliography 201 

Hepworth, John. On the Structure of the Foot of the Fly. 
Quar. Jour. Micro. Set., II, 1859, pp. 158-563. One plate 
showing feet of different flies. A review of the older theories 
of how a fly was able to walk on smooth surfaces. 

Herms, W. B. The Essentials of House-fly Control. Bull, of 
Berkeley Board of Health, Berkeley, Cal., 1909. Recommends 
removing manure as soon as possible and keeping it in tight 
bins until removed. No very satisfactory insecticides have 
been found for use in treating manure piles. 

Herms, W. B. The Berkeley House-fly Campaign. Cal. Jour, 
of Technology, Vol. XIV, No. 2, 1909. Discusses the methods 
that have been used in fighting the fly in Berkeley, Cal. Re- 
moving manure regularly or keeping it in closed bins recom- 
mended. 

Hewitt, C. G. A Preliminary Account of the Life-history of 
the Common House-fly. Mem. and Proc. Manchester Lit. 
Phil. Soc, 1906, Vol. 51, pp. 1-4. 

Hewitt, C. G. On the Bionomics of Certain Calyptrate Mucidae 
and Their Economic Significance with Especial Reference to 
Flies Inhabiting Houses. Jour. Econ. Biol., 1907, Vol. II, 
pp. 79-88. Character and importance of group and notes on 
many species. 

Hewitt, C. G. Structure, Development and Bionomics of the 
House-fly, Muca domestica. Part I, Quar. Jour. Micro. Sci., 
1907, p. 395, on anatomy, external and internal, and bibli- 
ography. Part II, same; 1908, p. 495. Breeding-habits, 
development and anatomy of larvae, bibliography. Part III, 
same; 1909, pp. 347-414. The bionomics, allies, parasites, 
and the relations to human disease. The best article on the 
house-fly. 

Howard, L. O. Further Notes on the House-fly. Bull. 10, 
U. S. Dept., Agric. Div. of Ento., p. 63, 1898. Experiments 
to kill larvae in manure. 

Howard, L. O. House-flies. U. S. Dept. of Agric, Bureau of 



202 Insects and Disease 

Ento., Circular No. 71, revised ed., 1906. Methods of control 
of house-fly and related species. 

Howard, L. O., and Marlatt, C. L. Bull. 4, U. S. Dept. 
Agric, Div. of Ento., pp. 43-47, 1896. General account with 
methods of controlling. 

Jepson, F. P. The Breeding of the Common House-fly During 
the Winter Months. Jour. Econ. Biol., 4, 1909, pp. 78-82. 
Records of certain experiments which show that the flies will 
breed in winter under favorable conditions. 

Newstead, R. Preliminary Report on the Habits, Life-cycle 
and Breeding-places of the Common House-fly as Observed 
in the City of Liverpool, with Suggestions as to the Best Means 
of Checking Its Increase. Liverpool, Oct. 3, 1907. 

Newstead, R. On the Habits, Life-cycle and Breeding-places 
of the Common House-fly. Ann. Trop. Med. Para., Vol. I, 
No. 4, Feb. 29, 1908, pp. 507-520. Final report on this sub- 
ject. Sums up notes on life-history, habits, breeding-places, 
etc. Important article. 

Packard, A. S. On the Transformation of the Common House- 
fly with Notes on Allied Forms. Proc. Boston Soc. Nat. Hist., 
Vol. XVI, 1874, pp. 136-140. Life-history and anatomy. 

Wilcox, E. V. Fighting the House-fly. Country Life in Amer- 
ica, May, 1908. Methods of controlling this pest. 

HOUSE-FLIES AND TYPHOID 

Austen, E. E. The House-fly and Certain Allied Species as 
Disseminators of Enteric Fever Among the Troops in the 
Field. Jour. Roy. Army Med. Corps, June, 1904. Suggests 
that it may carry enteric fever and other diseases; method of 
control. 

Felt, E. P. The Typhoid or House-fly and Disease. In 24th 
Rept. of State Ento. in N. Y. State Museum Bull., No. 455, 
1909. A general discussion with complete bibliography. 



Bibliography 203 

Firth, R. H., and Horrocks, W. H. An Inquiry Into the In- 
fluence of Soil, Fabrics, and Flies in the Dissemination of 
Enteric Infection. Brit. Med. Jour., Vol. II, 1902, pp. 936- 
942. House-flies carry enteric bacilli. They may pass through 
digestive tract and remain virulent. 

Hamilton, Alice. The Fly as a Carrier of Typhoid. Jour. 
Amer. Med. Assn., 40, 1903, pp. 576-83. A study of a typhoid 
outbreak in Chicago gives good evidence that the flies were 
important factors in the spread of the disease. 

Hewitt, C. G. The Biology of House-flies in Relation to 
Public Health. Royal Inst. Pub. Health Jour., Oct., 1908. 

Howard, L. O. A contribution to the Study of the Insect 
Fauna of Human Excrement. Proc. Wash. Acad. Sci., 2, 

1900, pp. 541-600. Special reference to the house-fly and 
typhoid fever. 

Howard, L. O. Flies and Typhoid. Pop. Sci. Mo., Jan., 

1901, pp. 249-256. A popular account of several species of 
flies that may be concerned in carrying typhoid. 

Klein, E. Flies as Carriers of B. typhus. Brit. Med. Jour., 
Oct. 17, 1908, pp. 1150-51. In cultures made from flies he 
found great numbers of B. coli communis and B. typhosus, 
showing that flies may carry these germs. 

Martin, A. Flies in Relation to Typhoid and Summer Diarrhea. 
Public Health, 15, 1903, pp. 652-653. Believes that the 
house-fly is largely responsible for these diseases. 

Reed, Walter. War Dept. An. Rept., 1899, pp. 627-633. 
Flies the cause of a typhoid outbreak in army in 1899. 

HOUSE-FLY AND VARIOUS DISEASES 

Buchanan, R. A., Glasg, F. F., and M. B. The Carriage 
of Infection by Flies. Lancet, 173, 1907, pp. 216-218. Flies 
carry various germs on their feet and distribute them where 
they walk. Must protect food from contamination. 



204 Insects and Disease 

Brewster, E. T. The Fly. The Disease of the House. Mc- 
Clures Magazine, XXXIII, No. 5, Sept., 1909, pp. 564-568. 
Proposes to make use of tropisims for ridding the houses of 
flies. 

Castellani, Aldo. Experimental Investigation on Frambcesia 
tropica (Yaws). Jour, of Hyg., Vol. VII, 1907, pp. 558-599. 
On pages 566-568 he discusses the part played by insects in 
transmitting the disease. Gives detail of experiments con- 
ducted and concludes that under certain conditions yaws may 
be conveyed by flies and possibly other insects. 

Cobb, J. O. Is the Common House-fly a Factor in the Spread 
of Tuberculosis? Amer. Med., 9, 1905, pp. 475-477. Be- 
lieves that the bacilli may enter the system through the di- 
gestive tract and that flies carry them to our food. 

Dickenson, G. K. The House-fly and Its Connection with 
Disease Dissemination. Med. Record, 71, 1907, pp. 134-139. 
Summary; bibliography. 

Esten, W. M., and Mason, C. J. Sources of Bacteria in Milk. 
Storr's Agric. Ex. Stn., Conn. Bull., 51, 1908. Shows how 
flies may carry bacteria to milk. Table showing number of 
bacteria on flies from various sources. 

Felt, E. P. The Economic Status of the House-fly. Jour. Eco. 
Ento., Vol. 2, No. 1, Feb., 1909, pp. 39-45. A summary of 
the charges, possibilities, proofs, etc. Discussion. 

Gudger, E. W. Early Note on Flies as Transmitters of Disease. 
Science, N. S. Vol. 31, Jan. 7, 1910, pp. 31-32. 

Hamer, W. H. Nuisance from Flies. London County Council 
Rept. No. 1,138, pp. 1-10, and No. 1,207, pp. 1-6, 1908. 
Observations on various flies and their relation to dis- 
eases. 

Hayward, E. H. The Fly as a Carrier of Tuberculosis Infec- 
tion. N. Y. Med. Jour., 80, 1904, pp. 643-644. Tubercular 
bacilli pass through the digestive tract of flies and remain 
virulent. 



Bibliography 205 



Howard, L. O. The Carriage of Disease by Flies. Bull. 30, 
N. S., pp. 39-45, U. S. Dept. Agric, Div. of Ento., 1901. 
Discussion of flies as carriers of disease. 

Howard, L. O. House-flies. U. S. Dept. of Agric, Bureau of 
Ento., Cir. No. 71, revised ed., Sept. 21, 1906. Notes on the 
various species visiting houses; habits; methods of control; 
regulations for controlling flies in cities. 

Hutchinson, Woods. The Story of the Fly That Does Not 
Wipe Its Feet. Sat. Evening Post, March 7, 1908. 

Jackson, Daniel D. Conveyance of Disease by Flies Sum- 
marized. Bost. Med. & Surg. Jour., 1908, p. 451. Disease 
and flies prevail at same time; records over 1,000,000 bacteria 
to each fly caught on swill-barrels. 

Jackson, Daniel B. Pollution of New York Harbor as a 
Menace to Health by the Dissemination of Intestinal Diseases 
Through the Agency of the Common House-fly. Account of 
experiments and deductions. Pamphlet issued July, 1908, by 
Merchants' Assn. of New York. 

Leidy, Joseph. Flies as a Means of Communicating Contagious 
Diseases. Proc. Acad. Nat. Sci. Phil., 23, 1871, p. 297. Be- 
lieves that flies may carry disease; refers to flies in connection 
with gangrene and wounds. 

Lord, F. T. Flies and Tuberculosis. Bost. Med. & Surg. 
Jour., 1904, pp. 651-654. Fly-specks may contain virulent 
tubercular bacilli for at least fifteen days. 

Mays, Thos. J. The Fly and Tuberculosis. N. Y. Med. Jour. 
& Phila. Med. Jour., 82, 1905, pp. 437-438. Believes that 
J. O. Cobb's data as given in Amer. Med. Jour, is not at all 
conclusive. 

Nash, J. C. T. A Note on the Bacterial Contamination of Milk 
as Illustrating the Connection Between Flies and Epidemic 
Diarrhea. Lancet, II, 1908, pp. 1668-69. Experiments show 
that milk left exposed to flies soon contains many more germs 
than that protected from them. 



206 Insects and Disease 

Nash, J. C. T. The Etiology of Summer Diarrhea. Lancet, 
164, 1903, p. 330. Believes house-fly carries this disease be- 
cause the two appear and disappear together. 

Robertson, A. Flies as Carriers of Contagion in Yaws. Jour. 
Trop. Med. & Hyg., 11, 1908, No. 14, p. 213. As a result 
of examinations the author concludes that the house-fly is 
capable of carrying the virus of yaws. 

Sandilands, J. E. Epidemic Diarrhea and the Bacterial Con- 
trol of Food. Jour. Hyg., 6, 1906, pp. 77-92. Believes that 
house-flies convey these diseases from the excrement of in- 
fected infants. 

Sibthorpe, E. H. Cholera and Flies. Brit. Med. Jour., Sept., 
1896, p. 700. Flies considered scavengers, think they thus 
help abate the disease. 

Smith, T. The House-fly as an Agent in Dissemination of In- 
fectious Diseases. Amer. Jour. Pub. Hyg., Aug., 1908, 
pp. 312-317. Points out that flies on account of their habits, 
are dangerous sources of contamination. 

Smith, Theobald. The House-fly at the Bar. Merchants' 
Assn., New York, 1909, pp. 1-48. Letters from various 
authorities giving their opinion; quotations from various 
authors. Bibliography. 

Veeder, M. A. Flies as Spreaders of Sickness in Camps. Med. 
Record, 54, 1898, pp. 429-430. Flies feed on typhoid excreta 
and pass to food. Cultures made from fly tracks and excreta 
show many bacteria present. 

Veeder, M. A. The Relative Importance of Flies and Water 
Supply in Spreading Disease. Med. Record, 55, 1899, pp. 10- 
12. Reasons for believing that flies spread disease in many 
instances. Burial of infected typhoid material no protection 
but a menace. 

Dangers from Flies. E. P. W. Nature, Vol. 29, pp. 482-483. 
Review of an article by Dr. B. Grassi in regard to flies and 
various diseases. Opthalmia is discussed. Flies may ingest 



Bibliography 207 

and pass unharmed eggs of various human parasites including 
tapeworm. 

HUMAN MYIASIS 

Allen, Chas. H. Demonstration of Locomotion in the Larva? 

of the OEstridse. Proc. Amer. Assn. Adv. Sci., Vol. 24, 1875, 

pp. 230-236. Larvae taken from flesh of child, one had moved 

thirty-six inches and one six inches. 
French, G. H. A Parasite the Supposed Cause of Some Cases 

of Epilepsy. Canad. Ento., 32, 1900, pp. 263-264. Larvae of 

Gastrophilus or Dermatobia in the alimentary canal supposed 

to have caused spasms in young boy. 
Gilbert, N. C. Infection of Man by Dipterous Larvae with 

Report of Four Cases. Archives of Internal Med., Oct., 1908. 

Historical; various kinds sometimes found in man; good 

summary of subject. Bibliography. 
Harrison, J. H. H. A Case of Myiasis. Jour. Trop. Med. &° 

Hyg., XI, Oct. 15, 1908, p. 305. Over 300 larvae of Lucilia 

macellaria removed from face of negro woman. 
Humbert, Fred. Lucilia macellaria Infesting Man. Proc. U. S. 

Nat. Museum, 6, 1883, pp. 103-104. Records several cases 

in which the screw-worm infested patients. 
Jenyus, Leonard. Trans. Ento. Soc, London, Vol. II, 1839, 

pp. 152-159. Notice of a case in which the larvae of a dipterous 

insect, supposed to be Anthomyia canicularis, Meig., were 

expelled in large quantities from the human intestines. 
Kane, E. R. A Grub Supposed to Have Traveled in the Human 

Body. Insect Life, II, 1890, pp. 238-239. Larva of bot-fly 

taken from face of boy. It had been traveling under the skin 

for about five months. 
McCampbell, E. F., and Cooper, H. J. Myiasis intestinalis 

Due to Infection with Three Species of Dipterous Larvae. 

Jour. Amer. Med. Assn., 53, Oct. 9, 1909, pp. 1160-62. Gen- 



208 Insects and Disease 

eral notes on this subject and a report on a case in which 
larvae of three different species of flies were obtained from one 
patient. 

Meinert, Fr. Lucilia nobilis Parasitic on Man. Insect Life, 
II, 1892, pp. 36-37. Two larvae from the ear of a man proved 
to be the above species. 

Mtjrtfeledt, M. E. Hominivorous Habits of the Screw-worm 
in St. Louis. Insect Life, IV, 1891, p. 200. Many larvae of 
this species removed from the nasal passages of a patient. 

Nelson, J. B. Insects in the Human Ear. Insect Life, VI, 1893, 
p. 56. Two cases in which blow-fly larvae are reported as 
coming from the human ear. 

Riley, W. A. A Case of Pseudoparasitism by Dipterous Larvae. 
Canad. Ento., 38, 1906, p. 413. Several larvae, species un- 
determined, removed from back of patient. 

Say, Thomas. On a South American Species of CEstrus Which 
Inhabits the Human Body. Tr. Phil. Acad. Nat. Sci., Vol. 2, 
1822, pp. 353-360. Extended notes on various dipterous 
larvae infesting man. 

Snow, F. H. Hominivorous Habits of Lucilia macellaria "The 
Screw-worm." Psyche, 4, 1883, pp. 27-30. Cites observa- 
tions made by himself and others. 

Williston, S. W. The Screw-worm Fly Compsomyia macellaria. 
Psyche, 4, 1883, pp. 112-114. Notes on this species with a 
translation of a Spanish article by Anibalzaga in which in- 
stances of this fly infesting human beings are recorded. 

Yount, C. E., and Sudler, M. T. Human Myiasis from the 
Screw-worm Fly. Jour. Amer. Med. Assn., Vol. 49, No. 23, 
1907, p. 1912. Several cases giving reference to literature, 
symptomatology, diagnosis. 

STOMOXYS AND OTHER FLIES 

Austen, E. E. Blood-sucking and Other Flies Known or 
Likely to Be Concerned in the Spread of Disease. In Albutt's 



Bibliography 209 

and Rolleston's System of Med., 2, 1907, pp. 169-186. A 
descriptive list of these flies. Bibliography. 

Austen, E. E. Illustrations of African Blood-sucking Flies 
Other Than Mosquitoes and Tsetse-flies. London, 1909. 

Newstead, R. On the Life-history of Stomoxys calcitrans. 
Jour. Econom. Biology, Vol. I, 1906, pp. 157-166. Describes 
habits and life-history of larvae and adults. Important article. 

Stephens, J. W. W., and Newstead, R. The Anatomy of 
the Proboscis of Biting Flies. Part II, Stomoxys. Ann. of 
Trop. Med. &> Parasit., Vol. I, No. 2, June 15, 1907, pp. 171- 
182. Good anatomical paper. Part I (Glossina) was pub- 
lished in mem. XVIII, 1906, Liverpool School Trop. Med. 

Tullock, F. Internal Anatomy of Stomoxys. Proc. Roy. Soc, 
London, 77, Series B, 1906, pp. 523-531. Descriptions and 
drawings comparing with Glossina. 



TSETSE-FLIES 

Austen, E. E. A Monograph of the Tsetes-flies. Published by 
order of the Trustees of the British Museum, 1903. 

Manson, P. Tsetse-flies. In Trop. Diseases, p. 174. Descrip- 
tion of genus; table of species; distribution; reproduction, 
habits. 

MiNcmN, E. A. Report of Anatomy of the Tsetse-fly {Glossina 
palpalis). Proc. Roy. Soc, London, 76, Series B, 1905, pp. 531- 
547. Good account of internal anatomy of this fly, important 
because of its relation to trypanosomiasis. 

Minchin, E. A. The Breeding-habits of the Tsetse-fly. Nature, 
Oct. 25, 1906, p. 636. 

Minchin, E. A., Gray, A. C. H., and Tullock, F. M. G. 
(Sleeping Sickness Com.) Glossina palpalis in Its Relation 
to Trypanosoma gambiense and Other Trypanosomes (Pre- 
liminary Report). Proc. Roy. Soc, Vol. 78, 1906, pp. 242-258. 
Report on certain experiments in feeding these flies on in- 



210 Insects and Disease 

fected animals and in allowing supposedly infected flies to 
feed on various animals. 
Now, F. G. The Trypanosomes of Tsetse-flies. Jour. Infec. 
Dis., Ill, 1906, pp. 394-411. Notes on the various species. 

TRYPANOSOMES AND TRYPANOSOMIASIS 

Bruce, David. Trypanosomiasis. Osier's Mod. Med., Vol. I, 

1907, p. 460. A discussion of Trypanosoma lewisi, evansi, 
brucei, gambiensi, and the diseases caused by them. 

Dutton, J. E., Todd, J. L., and Harrington, J. W. B. 
Trypanosome Transmission Experiments. Am. Trop. Med. 
cV Parasit., Vol. I, No. 2, June 15, 1907, pp. 201-229. Sec- 
tions on attempts to transmit trypanosomes by tsetse-flies; 
by other blood-sucking Arthropods, etc., conclude that try- 
panosomes may be mechanically transmitted by the bite of 
blood-sucking Arthropods. 

Hooker, W. A. Descriptions of Certain Trypanosomes, and 
Review of the Present Knowledge of the Role of Ticks in the 
Dissemination of Disease. Jour. Econ. Ento., Vol. I, No. 1, 

1908, pp. 65-76. Good review, tables and literature. 
Minchin, E. A. Investigations on the Development of Try- 
panosomes in Tsetse-flies and Other Diptera. Quart. Jour. 
Micro. Sci., 1908, pp. 159-260. 

Musgrove, W. E., and Clegg, M. T. Trypanosomes and 
Trypanosomiasis, with Special Reference to Surra in the Philip- 
pine Islands. Biological Lab., Bull. No. 5, Manila, 1903. Dis- 
cuss flies, fleas, mosquitoes, lice and ticks as possible dissemi- 
nators of the disease. 

Now, T. G., McNeal, M. J., and Torry, H. M. The Try- 
panosomes of Mosquitoes and Other Insects. Jour. Infec. 
Diseases, TV, 1907, pp. 223-276. These parasites often found 
in mosquitoes and other insects. Bibliography. 

Nuttall, G. H. F. The Transmission of Trypanosoma lewisi 



Bibliography 211 

by Fleas and Lice. Parasitology, Vol. I, No. 4, Dec, 1908, pp. 
296-301. This rat trypanosome is transmitted by fleas and lice. 

Old, J. E. S. Contribution to the Study of Trypanosomiasis 
and to the Geographical Distribution of Some of the Blood- 
sucking Insects, etc. Jour. Trop. Med. &° Hyg., 12, Jan. 15, 
1909, pp. 15-22. Notes on blood-sucking Diptera and ticks. 

Rogers, Leonard. The Transmission of the Trypanosoma 
evansi by House-flies and Other Experiments Pointing to the 
Probable Identity of Surra of India and Nagana or Tsetse-fly 
Disease of Africa. Proc. Roy. Soc, Vol. LXVIII, 1901, 
pp. 163-170. 

Thimm, C. A. Bibliography of Trypanosomiasis; embracing 
original papers published prior to April 1909, and references 
to works and papers on tsetse-flies. London, 1909. 

Todd, J. L. A Note on Recent Trypanosome Transmission 
Experiments. Jour. Trop. Med. &° Hyg., 12, Sept., 1909, 
p. 260. Show that they develop in G. palpalis when taken from 
their mammal host at the proper stage of development. 

Woodcock, H. M. The Haemoflagellates: a Review of Present 
Knowledge Relating to the Trypanosomes and Allied Forms. 
Quar. Jour. Micro. Sci., Vol. 50, 1906, pp. 151-331. Char- 
acteristics; mode of infection; effects on host; biological con- 
siderations; life-cycle, etc. Spirochacke; bibliography. Im- 
portant article. 

Trypanosomiasis and Sleeping Sickness. Jour. Trop. Med. & 
Hyg., II, pp. 146-147, 162, 179-180, 196. List of recent 
literature. 

SLEEPING SICKNESS 

Bagshawe, A. G. Recent Advances in Our Knowledge of 
Sleeping Sickness. Lancet, II, 1909, pp. 1193-97. A summing 
up of the important discoveries of the preceding year. 

Hearsey, H. Sleeping Sickness. Jour. Trop. Met. &> Hyg., 
12, Sept. 1, 1909, pp. 263-264. Report on work accomplished 



212 Insects and Disease 

particularly in relation to the distribution of Glossina and other 
biting flies. 

Jarvis, C. Sleeping Sickness. Internat. Clinics, Vol. II, 1904, 
pp. 37-44. Shows the relation of the tsetse-fly to this disease. 

Lankester, E. R. The Sleeping Sickness. Quar. Review, 
July, 1904, p. 1 13. Discovery and early history; the fly, the para- 
site ; other related parasites. Relation of parasites to their hosts. 

Minchin, E. A. The ^Etiology of Sleeping Sickness. Nature, 
Nov. 15, 1906, pp. 56-59. 

Wollaston, A. F. R. Amid the Snow Peaks of the Equator: 
a Naturalist's Explorations Around Ruwenzori, with an 
Account of the Terrible Scourge of Sleeping Sickness. Nat. 
Geo. Mag., XX, No. 3, Mar., 1909. Abstracted from "From 
Ruwenzori to the Congo" by above author. 

Reports of the Sleeping Sickness Com. of the Royal Society, 
I to IX, 1903 to 1908. Studies and experiments with the 
trypanosomes and flies concerned in this disease. Later arti- 
cles by this commission are to be found in the Pro. Royal Soc, 
Series B, LXXXI and LXXXII. 

Sleeping Sickness Bureau Bulletins, 1 to 14, 1908-1910. Records 
of studies and experiments with trypanosomes and tsetse- 
flies, etc. 

Transmission of Sleeping Sickness. Editorial in Jour. Amer. 
Med. Assn., 53, Oct. 2, 1909, pp. 1104-05. Reviews recent 
experiments and studies. 

ROCKY MOUNTAIN FEVER AND TICKS 

Anderson, J. F. Spotted Fever (Tick Fever) of the Rocky 
Mountains. Hyg. Lab. Pub. Health and Mar. Hospt. Ser. f 
Bull. 14, 1903. Distribution, aetiology, etc. Believes that 
ticks are responsible for the transmission of the disease. 

Cooley, R. A. Preliminary Report on the Wood-tick. Bull. 75, 
Mont. Ex. Stn., 1908. Sums up Ricketts' finding; notes on 
life-history in laboratory and field. 



Bibliography 213 

King, W. W. Experimental Transmission of Rocky Mountain 
Fever by Means of the Tick. Preliminary note. Pub. Health 
and Mar. Hospt. Ser., 21, July 27, 1906, pp. 863-864. Con- 
veyed this fever from one guinea-pig to another by means of 
the tick. 

Ricketts, H. T. The Transmission of Rocky Mountain Fever 
by the Bite of the Wood-tick (Dermacentor occidentalis) . Jour. 
Amer. Med. Assn., Vol. 47, Aug., 1906, p. 358. Guinea-pig 
successfully inoculated by means of tick. 

Ricketts, H. T. The Role of the Wood-tick {Dermacentor 
occidentalis) in Rocky Mountain Spotted Fever. Jour. Amer. 
Med. Assn., Vol. 49, July 6, 1907, pp. 24-27. Notes on ex- 
periments conducted and studies made. Takes position that 
these experiments connect the tick with the transmission of 
the fever. 

Robinson, A. A. Rocky Mountain Spotted Fever. Med. Rec, 
Nov. 28, 1908. Occurrence and distribution of the disease; re- 
view of the various theories in regard to its transmission. P. E. 
Jones of Salt Lake believes it is transmitted by mosquitoes. 

Stiles, C. W. A Zoological Investigation Into the Cause, 
Transmission and Source of Rocky Mountain Spotted Fever. 
Hyg. Lab. Pub. Health and Mar. Hospt. Ser., Bull. 20, 1905. 
Does not find the parasite that had been recorded by others, 
and finds no evidence to indicate that the ticks transmit the 
disease. 

Wilson, L. B., and Channing, W. M. Studies in Pyroplasmosis 
hominis (Spotted Fever or Tick Fever of the Rocky Moun- 
tains). Jour. Infec. Diseases, 1, 1904, pp. 31-57. Evidence 
that the disease is transmitted solely by means of the ticks. 

TICKS AND VARIOUS DISEASES 

Banks, Nathan. Tick-borne Diseases and Their Origin. Jour. 
Eco. Ento., Vol. I, No. 3, 1908, pp. 213-215. Shows how 



214 Insects and Disease 

ticks may become important disease-carriers by changing their 
hosts as the normal host is exterminated, or for other reasons. 

Banks, Nathan. A Revision of the Ixodoidea or Ticks of the 
United States. Tech. Series No. 15, Bull, of Bureau of Ento., 
U. S. Dept. Agric, 1908. Structure, life-history, classification, 
catalogue, bibliography. 

Barber, C. A. The Tick Pest in the Tropics. Nature, 52, 
1895, pp. 197-200. Direct and indirect effects of ticks on 
their hosts. 

Christy, C. Ornithodoros moubata and Tick Fever in Man. 
Brit. Med. Jour., Vol. II, 1903, p. 652. Relation of the tick 
to Filaria perstans. 

Dutton, J. E., and Todd, J. L. The Nature of Human Tick 
Fever in the Eastern Part of the Congo Free State with Notes 
on the Distribution and Bionomics of the Tick. Liverpool 
School of Tropical Medicine. Memoir, 17, Nov., 1905, pp. 1-18. 

Hooker, W. A. A Review of the Present Knowledge of the Role 
of Ticks in the Transmission of Disease. Jour. Eco. Ento., 
Vol. I, No. 1, 1908, p. 65. Review of the subject; table show- 
ing zoological position of parasites transmitted by ticks. 
Table showing zoological position of ticks. 

Hooker, W. A. Life-history, Habits and Methods of Study of 
the Ixodoidea. Jour. Eco. Ento., Vol. I, No. 1, 1908, p. 34. 
Notes on several species, especially M. annulatus. Host re- 
lationship; adaptations as factors in host relationship; mating; 
geographical distribution; methods of breeding, etc. 

Hooker, W. A. Some Host Relations of Ticks. Jour. Eco. 
Ento., Vol. 2, No. 3, 1909, p. 251. Notes on ticks found on 
various hosts. 

Hunter, W. D., and Hooker, W. A. Information Concern- 
ing the North American Fever Tick with Notes on Other 
Species. Bull. 72, Bureau 0} Ento., 1907. Life-history, host 
relation, etc., of fever tick; classification and notes on other 
species; bibliography divided into sections. 



Bibliography 215 

Lounsbury, C. P. Habits and Peculiarities of Some South 
African Ticks. Rept. of the Brit. Assn. for the Advancement of 
Sri., 1905 (South Africa), pp. 282-291. 

McCrae, Thomas. Relapsing Fever. Osier's Mod. Med., 
Vol. II, p. 245, 1907. ^Etiology, symptoms, treatment, etc. 
(Apparently communicated by blood-sucking insects.) 

Newstead, R. On the Pathogenic Ticks Concerned in the 
Distribution of Diseases in Man. Brit. Med. Jour., II, 1905, 
pp. 1695-97. Classification and habits, particularly of Orni- 
thodoros moubata. 

Nuttall, G. H. F. The Ixodoidea or Ticks. Jour, of Roy. 
Inst, of Pub. Health, 1908. List of disease-bearing ticks. 
Position of ticks, classification. Biology. Preventive measures. 

Nuttall, G. H. F. Piroplasmosis. Jour. Roy. Inst, of Pub. 
Health, 1908. What piroplasma are; diseases produced by 
them. Biology. 

Nuttall, Geo. F., and co-workers. Canine Piroplasmosis, 
Parts I to VI. Jour. Hyg., Vol. 4, No. 2, Apr., 1904, to Vol. 7, 
No. 2, Apr., 1907. A thorough discussion of the disease, the 
parasite which causes it and the ticks which convey it. 

Pocock, R. I. Ticks. In Albutt and Rolleston's System of 
Med., II, 1907, pp. 187-203. Classification; description of the 
best-known pathogenic species. Extended bibliography. 

Skinner, B. Preliminary Note on Ticks Infecting the Rats 
Suffering from the Plague. Brit. Med. Jour., Vol. II, 1907, 
p. 457. Records taking tick on a plague-sick rat and finding 
bacilli similar to plague bacilli in connection with it. 

Smith, T., and Kilborne, F. L. Texas Fever. U. S. Dept. 
Agric. Bureau of Animal Industry, Bull. No. 1, 1893. Records 
of the experiments showing disease to be transmitted by 
ticks. 

Wellman, F. C. Preliminary Note on Some Bodies Found in 
Ticks — Ornithodoros moubata — Fed on Blood Containing 
Embryos of Filaria. Brit. Med. Jour., July 20, 1907, p. 142. 



2i 6 Insects and Disease 

Believes that F. perstans is conveyed from man to tick and 
from tick to man. 

KALA-AZAR AND BEDBUGS 

Giratjlt, A. A. The Indian Bedbug and Kala-azar Disease. 
Set., N. S., Vol. XXV, 1907, p. 1004. Indian bedbug is 
C. rotundatus Sig. Its distribution. Summary of Dr. Patton's 
paper on " Preliminary Report on the Development of the 
Leishman-Donovan Body in the Bedbug." 

Patton, W. S. The Development of the Leishman-Donovan 
Parasite in Cimex rotundatus. Scientific Mem. of Gov. of 
India, Nos. 27 and 31, 1907. Traces the development of this 
parasite; believes that the bedbug is concerned in transmitting 
this disease. 

See also Manson's Tropical Diseases, pp. 178-190. 

TEXT OR REFERENCE BOOKS IN WHICH THE RE- 
LATION OF INSECTS TO VARIOUS DISEASES IS 
DISCUSSED 

Abbott, A. C. Hygiene of Transmissible Diseases. Phil., 
1899. Causes, modes of dissemination, prevention, treatment 
of infectious and contagious diseases. 

Allbutt, T. C, and Rolleston, H. D. A System of Medicine. 
London, 1907. Vol. II, Pt. II, contains sections on tropical 
diseases; animal parasites and the diseases they carry and 
zoological articles dealing with Protozoa, mosquitoes, flies and 
ticks. All articles have bibliographies, some of them quite 
extensive. 

Balfour, Andrew. Review of Recent Advances in Tropical 
Medicine. Supplement to Third Rept. Wellcome Research Lab., 
London, 1908. Notes, extracts and references in regard to 
important articles during the preceding few months. 



Bibliography 217 

Daniels, C. W. Studies in Laboratory Work, 2d ed., London, 
1907. A good discussion of animal parasites in the blood and 
blood- plasma; development of malarial parasites in mosquitoes; 
flies, fleas, lice, bedbugs, ticks, etc. 

Jackson, C. W. Tropical Medicine. Phil., 1907. Discusses 
diseases due to bacteria and the parasites and uncertain 
causes. Splendid recent summary of the various ways in 
which the different diseases are disseminated. 

Langfeld, Millard. Introduction to Infectious and Parasitic 
Diseases, Including Their Causes and Manner of Transmis- 
sion. Phil., 1907. Chapters on infection, animal parasites, 
avenues of exit and portals of entry of infectious agents and 
parasites into the body. 

Manson, Patrick. Lectures on Tropical Diseases. London, 
1905. Delivered at Cooper Medical College, 1905. Dis- 
cusses several of these diseases. Last chapter on problems 
in tropical medicine. 

Manson, Patrick. Tropical Diseases. London, 1907, Dis- 
eases of the tropics discussed in a very comprehensive manner. 
Considerable attention given to the part played by insects in 
the transmission of many of the diseases. 

Metchnikoff, E. Immunity in Infectious Diseases. (Trans. 
from the French by F. G. Binnie.) Cambridge, 1905. Splendid 
discussion of various kinds of immunity. Insects referred to 
occasionally. 

Osler's Modern Medicine. Vol. 1, 1907, Pt. VI, Diseases Caused 
by Protozoa. Part VII, Diseases Caused by Animal Parasites. 
Vol. II, 1907, Infectious Diseases. Vol. Ill, Infectious Diseases 
(cont). One of the best and most modern text-books; the 
volumes noted above contain many references to the relation 
of insects to the particular diseases under discussion. 

Park, W. H. Pathogenic Micro-organisms, Including Bacteria 
and Protozoa. N. Y., 1908. These organisms comprehensively 
treated. 



2i 8 Insects and Disease 

Ricketts, H. T. Infection, Immunity and Serum Therapy. 
Chicago, 1906. Chapters on parasitism, infection, contagion, 
immunity, various diseases, etc. 

Scheube, B. The Diseases of Warm Countries: a Handbook 
for Medical Men. Trans, from Ger. by Pauline Falcke, 
London, 1903. Sections on general infectious diseases, diseases 
caused by animal parasites, etc. Good bibliography of each 
disease treated. 

Simpson, W. J. R. The Principles of Hygiene as Applied to 
Tropical and Subtropical Climates. London, 1908. Occa- 
sional references to flies and mosquitoes as carriers of disease. 
Chapter XV deals with malaria and other diseases caused by 
mosquitoes. 

Wilson, J. C. Modern Clinical Medicine; Infectious Diseases. 
New York and London, 1905. Chapters on yellow fever, 
malarial diseases and plague; contains references to the rela- 
tion of insects to these diseases. 

MISCELLANEOUS ARTICLES 

Balfour, Andrew. Further Observations on Fowl Spiroche- 
tosis. Jour. Trop. Med. &> Hyg., 12, Oct. 1, 1909, pp. 285- 
289. Ticks and lice may carry this disease. 

Chittenden, F. H. Harvest-mites or "Chiggers." Circular 77, 
U. S. Dept. Agric. Bur. Ento., 1906, pp. 1-16. Descriptions 
of these pests and their habits. Remedies. 

Doty, A. H. The Means by Which Infectious Diseases Are 
Transmitted. Amer. Jour, of Med. Sci., 138, July, 1909, pp. 30- 
39. Flies and mosquitoes as disseminators of disease briefly 
discussed. 

Duncan, F, M. Industrial Entomology: the Economic Im- 
portance of a Study of Insect Life. Jour. Roy. Soc. Arts, 
May 22, 1908, pp. 688-696. A very interesting review of the 
subject of insects and disease. 



Bibliography 219 

Flexner, Simon. Science, N. S., Vol. 27, No. 682, Jan. 24, 
1908, pp. 133-136. On these pages the author discusses 
relation of bacteria and Protozoa to human diseases. 

Goldberger, Jos., and Shamberg, J. F. Epidemic of an 
Utricaroid dermatitis Due to a Small Mite (Pediculoides ventri- 
cosus) in the Straw of Mattresses. Pub. Health Rept., Pub. 
Health and Mar. Hospt. Ser., July 9, 1909, Vol. XXIV, No. 28. 
Experiments showed that a certain skin disease occurring 
during summer was due to this mite. 

Gorgas, W. C. The Part Sanitation Is Playing in the Con- 
struction of the Panama Canal. Jour. Amer. Med. Assn., 53, 
Aug. 21, 1909, pp. 597-599. Shows the changes that have 
been brought about by modern sanitation and the destroying 
of the mosquitoes' breeding-places. 

Howard, L. O. Hydrocyanic-acid Gas Against Household 
Insects. Circular 46, U. S. Dept. Agric, Div. of Ento., 1902. 
Directions for handling this dangerous gas. 

King, A. F. G. Insects and Disease; Mosquitoes and Malaria. 
Pop. Sci. Mo., XXIII, 1883, pp. 644-658. Extended article 
in which the author sums up the observations which led him 
to believe that malaria and other diseases were transmitted 
by the mosquito. One of the earliest articles on this subject; 
refers to an article in New Orleans Med. & Surg. Jour., 
Vol. IV, 1848, pp. 563-601, by Josiah Nott, who maintained 
that yellow fever was carried by mosquitoes. 

Manson, Patrick. Recent Advances in Science and Their 
Bearing on Medicine and Surgery. Jour. Trop. Med. & Hyg., 
XI, pp. 337-338, Sept. 16, 1908. Discussion of parasites and 
disease and their methods of dissemination. 

Newstead, R., Dutton, J. E., and Todd, J. L. Insects and 
Other Arthropoda Collected in the Congo Free State. Ann. 
Trop. Med. £r= Parasit., Vol. 1, No. 1, Feb. 1, 1907, pp. 3-100. 
An interesting paper giving notes on many insects that cause 
or carry disease. 



220 Insects and Disease 

Nuttall, G. H. F. Spirochetosis in Man and Animals. Jour. 

of Roy. Inst, of Pub. Health, 1908. Why Spirochetes should 

be regarded as Protozoa. Classification; list of blood-inhabiting 

forms; relapsing fevers; transmission by ticks and other 

Arthropods. 
O'Connell, M. D. The Oversea Transport of Insect-borne 

Disease. Jour. Trop. Med. & Hyg., XI, 43, Feb. 1, 1908. 

Refers to article in same journal (Jan. 15) and points out that 

malaria is very likely to be transmitted by mosquitoes in this way. 
Osborn, Herbert. Insects Affecting Domestic Animals. 

U. S. Dept. of Agric, Div. of Ento., Bull. No. 5, N. S., 1896. 

Discusses the various insect pests of man and domestic animals 

Host lists. Bibliography. 
Rickets, H. T., and Wilder, R. M. The Typhus Fever of 

Mexico. Jour. Amer. Med. Assn., LIV, No. 6, Feb. 5, 1910, 

p. 463. Believes this disease is transmitted by insects, probably 

lice. 
Ritchie, James. A Review of Current Theories Regarding 

Immunity. Jour. Hyg., 2, 1902, pp. 215-285, and pp. 452- 

464. Discussion of various theories. Bibliography. 
Shipley, A. E. On the Relation of Certain Cestode and Nema- 

toda Parasites to Bacterial Disease. Jour, of Eco. Biol., 4, 

1909, pp. 61-71. Shows that these parasites may often cause 

serious diseases by opening the way for malignant germs. 
Ward, H. B. Spirochetes and Their Relationship to Other 

Organisms. Amer. Nat., 42, 1908, No. 498, pp. 374-387. 

Still undecided as to whether they belong with bacteria or 

Protozoa, probably the latter. 
Ward, H. B. The Relation of Animals to Disease. Science, 

N. S., 22, 1905, pp. 193-203. An interesting, comprehensive 

review of the subject. 
Ward, Henry B. Relation of Animals to Disease. Transactions 

of Amer. Micro. Soc, Vol. 27, 1907, pp. 5-20. The various 

ways in which animals may produce or carry disease. 



Bibliography 221 

The Oversea Transport of Insect-borne Diseases. Editorial in 
Jour. Trop. Med. 6° Hyg., XI, Jan. 15, 1908, pp. 22-23. 
Points out the danger of yellow fever, plague and other diseases 
being borne overseas by infected insects. 

The Society for the Destruction of Vermin. Editorial in Jour. 
Trop. Med. 6° Hyg., XI, Apr. 15, 1908, p. 124. Tells of or- 
ganization of such society and its purposes. 



INDEX 



INDEX 



Adams, S. H., 132. 

Advisory Committee, 146. 

Agramonte, Dr. Aristides, 123. 

Alimentary canal, fly larvae in, 49. 

Amceba, 19. 

Anopheles, adults, 91; eggs, 92; 
habits of adults, 94; larvae, 78, 
79, 93; pupae, 93; resting po- 
sition, 92; species in U. S., 92. 

Anthrax, 44; and flies, 70. 

Arthropoda, 26. 

Asexual reproduction, in. 

Bacillus, anthracis, 44; icteroides, 

124; leprae, 171; pestis, 150. 
Bacillus carriers, 66. 
Back-swimmers, 100. 
Bacteria, 15; saprophytic and 

parasitic, 17; effect on host, 

18; dissemination, 18. 
Bedbugs, 54, 147. 
Banks, Nathan, 34. 
Bell-animalcule, 22. 
Berne, 51. 
Birds as enemies of mosquitoes, 

99. 
Black-flies, 46. 
Bltv^k-heads, 35. 
Blow-flies, 48. 
Blue, Dr. Rupert, 143. 
Blue-bottle flies, 48. 



Bot-flies, 50. 
Break-bone fever, 169. 
Breeze-fly, 44. 
Buffalo-gnats, 46. 

Calliphora vomitoria, 48. 

Camphor, for mosquitoes, 102. 

Cancer, 36. 

Carroll, Dr. James, 123. 

Castor-bean tick, 27. 

Cattle tick, 29. 

Cedar oil, for mosquitoes, 102. 

Ceratophyllus, faciatus, 153; acu- 

tus, 156. 
Cesspools, 72. 
Chigger, 53. 
Chigger-flea, 53. 
Chigo, 30, 39. 
Chigoe, 53. 
Cholera, 68. 

Chrysomyia macellaria, 47. 
Cimex, lectularis, 54; rotunda- 

tus, 173. 
Contagious diseases, 8. 
Conjugation, 20. 
Cooley, Prof. R. A., 33. 
Craig, Dr. C. F., 118. 
Ctenocephalus, canis, 154; felis, 

154. 
Culex, fatigans, 96, 170; pipiens, 



223 



224 



Index 



Dengue, 169. 

Dermatobia cyaniventris, 51. 
Dermatophilus penetrans, 53. 
Diarrhea, 69. 
Diptera, 43. 
Diving beetles, 100. 
Dragon-flies, 99. 
Dysentery, 20. 

Eggs, of flies, 63; of mosquitoes, 

77; of Anopheles, 92. 
Egyptian opthalmia, 52. 
Elephantiasis, 164. 
Enemies of mosquitoes, 97. 
Enteritis, 69. 
Euglena, 21. 
Eye- worm, 12. 

Face-mite, 35. 

Fighting mosquitoes, adults, 101; 
larvae, 103. 

Fiji Islands, Anopheles in, 117. 

Filaria bancrofti, 164. 

Finlay, Dr. Charles, 124. 

Fish, 100. 

Flagella, 20. 

Fleas, 52; and plague, 142, 145, 
147; structure and habits, 151; 
common species, 153; on 
ground squirrels, 156; reme- 
dies for, 157. 

Flies, 43; and typhoid, 65; 
specks, 66; and various dis- 
eases, 68. 

Flesh-flies, 48. 

Fumigating for mosquitoes, 102. 

Gad-fly, 43- 



Glossina palpalis, 163. 

Golgi, Camillo, 109. 

Grassi, Prof. G. B., 118. 

Gray-flies, 47. 

Ground squirrels and plague, 

155- 
Guinea- worm, 11. 

Haemamceba, 109. 
Haematobia, 45. 
Haemosporidiida, 24. 
Haemotopinus spinulosis, 55. 
Harvest-mite, 37. 
Havana, yellow fever in, 131. 
Hawaii, mosquitoes in, 98. 
Hemiptera, 54. 
Homalomyia canicularis, 49. 
Hoplopsyllus anomalus, 156. 
Horse bot-flies, 50. 
House-flies, 57; structure, 59; 

how they carry bacteria, 62; 

life-history and habits, 63; 

fighting, 71; and typhoid, 

65. 
Horse-flies, 43. 
Howard, Dr. L. O., 59, 73. 
Hyperparasitism, 3. 

Immunity, 5. 

Indian Plague Commission, 144. 

Infectious diseases, 8. 

Infusoria, 22. 

Insects, cause or carry disease, 
40; numbers, 40; annual loss 
caused by, 41; how they carry 
disease germs, 55. 

Irrigating ditches, 104. 

Itch-mite, 36. 



Index 



225 



Jackson, Dr. D. D., 67 
Jennings, 22. 
Jiggers, 38, 53. 
Jigger-flea, 53. 

Kala-azar, 173. 
Kerosene, 104. 
Koch, 44. 

Lamprey-eel, 2. 
Lancisi, J. M., 107. 
Larvae, of flies, 64; of mosqui- 
toes, 78. 
Laveran, A., 108. 
Laverania, 109. 
Lazear, Dr. Jessie W., 123. 
Leeuwenhock, Anton von, 

22. 
Lepra bacillus, 36. 
Leprosy, 36, 70, 171. 
Lice, 54. 
Linnaeus, 76. 
Little house-fly, 49. 
Lock-jaw, 18. 
Loemopsylla cheopus, 153. 
Low, Dr. A., 118. 
Lucilia spp., 48. 
Lugger, Prof. Otto, 38. 

Malaria, early theories in regard 
to, 106; parasite that causes, 
108; life history of parasite, 
109; parasite in mosquito, 113; 
summary, 117; experiments, 
118. 

Maggots, 63. 

Malta or Mediterranean fever, 
171. 



Mange, 37. 

Manure-fly, 59. 

Manson, Sir Patrick, 112, 
123. 

Mastigophora, 20. 

Melanin, no. 

Micrococcus melitensis, 171. 

Microbes, 10. 

Mites, 26, 35. 

Mouth-parts, of fly, 60; of mos- 
quito, 83. 

Mosquito, 76; abdomen, 86; 
adults, 81; Anopheles, 91; 
how they bite, 84; effect of 
bite, 87; blood, 90; how they 
breathe, 89; classification, 91; 
and dengue, 169; eggs, 77; 
and elephantiasis, 164; ene- 
mies, 77; fighting, adults, 101, 
larvae, 103; larvae, 78; and 
malaria, 106; malarial para- 
site in, 113; mouth-parts, 83; 
other species, 96; pupae, 80; 
salivary glands, 87; thorax, 85; 
and yellow fever, 94, 120. 

Mus, norvegicus, 154; rattus, 
154. 

Nanga, 45. 

Nematodes, 164. 

New Orleans, yellow fever in, 

120, 132. 
Noctiluca, 21. 
No-see-ums, 46. 

Ochromyia anthropophaga, 49. 
Oil of citronella, 102. 
Oil of pennyroyal, 102. 



226 



Index 



Oriental sore, 174. 
Ornithodorus moubata, 34. 
Oscinidae, 52. 

Otospermophilus beecheyi, 155. 
Ox-warbles, 50. 

Panama Canal zone, 135. 

Paramecium, 22. 

Parasite, denned, 1; classes of, 
4; in new regions, 5; diseases 
caused by, 7; effect on host, 9; 
relation to host, 14. 

Parasitism, 3. 

Pasteur, L., 44. 

Pearls, 13. 

Piroplasma bigeminum, 29. 

Plague, early history of, 142; 
fleas that transmit, 153; and 
flies, 70; and ground squirrels, 
155; how combatted in San 
Francisco, 143; results of 
other investigations, 150; Ver- 
jbitski's experiments, 147; 
work of Indian Plague Com- 
mission, 146. 

Plasmodium, 109. 

Protozoa, 19; classes of, 20. 

Proboscis, of fly, 60; of mos- 
quito, 80. 

Privies, 72. 

Privy-fly, 59. 

Pseudopodia, 20. 

Psoroptes communis, 37. 

Pulex irritans, 154. 

Punkies, 46. 

Pupae, of house-flies, 64; of 
mosquitoes, 80. 

Pyrethrum, 102. 



Rats, and plague, 143, 145; 

species of, 154. 
Red-bugs, 38. 
Reed, Dr. Walter, 123. 
Relapsing fever, 21, ^^. 
Rhizopoda, 20. 
Ricketts, Dr. H. F., 32. 
Rio de Janeiro, yellow fever in, 

137- 
Rocky Mountain spotted fever, 

32. 
Ross, Ronald, 112. 
Rucker, Dr. W. C, 143. 

Sacculina, 2. 
Salivary glands, 84, 87. 
Salt marshes, 97, 105. 
Sambon, Dr. L. W., 118. 
Sand-fleas, 53. 
Saprophytic bacteria, 17. 
Sarcophaga spp., 48. 
Sarcoptes scabiei, 37. 
Scab, 37. 
Screw- worm, 47. 
Seed-ticks, 27, 30. 
Sheep bot-flies, 51. 
Simmond, Dr. P. L., 145. 
Siphonaptera, 52. 
Skinner, Dr. H., 159. 
Sleeping sickness, 21, 161. 
Slipper animalcule, 22. 
Small-pox, 70. 
Smith, Dr. Theobald, 29. 
Smudges, 102. 
Sore-eye, 52. 
Spiders, 26. 
Spiracles, 89. 
Spirochaeta, 21, 130. 



Index 



227 



Spore formation, 24. 

Spores, 24. 

Sporozoa, 22. 

Spotted fever, 32. 

Stable-fly, 44, 75. 

Stegomyia, calopus, 94, 98, 139 

scutellaris, 96. 
Sticklebacks, 101. 
Stomoxys calcitrans, 44. 
Sulphur, 102. 
Surra, 45. 

Tabanus, 45. 
Tahiti, mosquitoes in, 96. 
Tapeworms, 2. 
Tetanus, 18. 
Texas fever, 28. 
Theobald, Dr. F. V., 76. 
Ticks, 26. 

Tidewater minnows, 101. 
Tobacco smoke, 102. 
Top-minnows, 98, 101. 
Torcel, 51. 
Tracheas, 89. 
Tracheal gills, 79. 
Trichina, 2. 
Trypanosome, 45, 161. 
Trypanosoma, evansi, 45; brucei, 
45; lewisi, 162; gambiensi, 162. 



Tsetse-fly, 45, 163. 

Tubercular bacilli, 69; germs, 

69. 
Typhoid-fly, 57, 59. 

Vaughan, Dr. W. C, 67. 
Ver macque, 51. 
Verjbitski, D. T., 147. 
Vorticella, 22. 

Water-boatmen, 100. 
Water-troughs, 104. 
Whip-bearers, 20. 
Whirligig beetles, 100. 
White, Surgeon J. H., 134. 
Wrigglers, 78. 

Yellow fever, 120; Commission, 
123; early observations on, 
121; experiments, 125; danger 
of in Pacific Islands, 140; in 
Havana, results of work on, 
131; history of in United 
States, 120; mosquito, 94; 
habits of, 95; in Panama 
Canal zone, 135; in Rio de 
Janeiro, 137; summary of re- 
sults of work on, 129. 



THE AMERICAN NATURE SERIES 

In the hope of doing something toward furnishing a series where 
the nature-lover can surely find a readable book of high authority, 
the publishers of the American Science Series have begun the publi- 
cation of the American Nature Series. It is the intention that in its 
own way, the new series shall stand on a par with its famous prede- 
cessor. 

The primary object of the new series is to answer questions 
which the contemplation of Nature is constantly arousing in the 
mind of the unscientific intelligent person. But a collateral object 
will be to give some intelligent notion of the "causes of things." 

While the cooperation of foreign scholars will not be declined, 
the books will be under the guarantee of American experts, and gen- 
erally from the American point of view; and where material crowds 
space, preference will be given to American facts over others of not 
more than equal interest. 

The series will be in six divisions : 

I. NATURAL HISTORY 

This division will consist of two sections. 

Section A. A large popular Natural History in several vol- 
umes, with the topics treated in due proportion, by authors of un- 
questioned authority. 8vo, 7ixl0£ in. 

The books so far publisht in this section are: 

FISHES, by David Starr Jordan, President of the Leland Stanford 
Junior University. $6.00 net; carriage extra. 

AMERICAN INSECTS, by Vernon L. Kellogg, Professor in the 
Leland Stanford Junior University. $5.00 net; carriage extra. 

BIRDS OF THE WORLD. A popular account by Frank H. 
Knowlton, M.S., Ph.D., Member American Ornithologists 
Union, President Biological Society of Washington, etc., etc., 
with Chapter on Anatomy of Birds by Frederic A. Lucas, 
Chief Curator Brooklyn Museum of Arts and Sciences, and edited 
by Robert Ridgway, Curator of Birds, U. S. National Museum. 
$7.00 net; carriage extra. 

Arranged for are: 

SEEDLESS PLANTS, by George T. Moore, Head of Department 
of Botany, Marine Biological Laboratory, assisted by other spe- 
cialists. 

WILD MAMMALS OF NORTH AMERICA, by C. Hart Mer- 
riam, Chief of the United States Biological Survey. 

REPTILES AND BATRACHIANS, by Leonhard Stejne»er, 
Curator of Reptiles, U. S. National Museum. 



AMERICAN NATURE SERIES (Continued) 

I. NATURAL HISTORY (Continued) 

Section B. A Shorter Natural History, mainly by the Authors 
of Section A, preserving its popular character, its proportional treat- 
ment, and its authority so far as that can be preserved without its 
fullness. Size not yet determined. 

II. CLASSIFICATION OF NATURE 

1. Library Series, very full descriptions. 8vo. 74xlO| in. 

Already publisht: 

NORTH AMERICAN TREES, by N. L. Brittok, Director of the 
New York Botanical Garden. $7.00 net; carriage extra. 

FERNS, by Campbell E. Waters, of Johns Hopkins University, 
$3.00 net; by mail, $3.30. 

2. Pocket Series, Identification Books — "How to Know," brief and 

in portable shape. 

III. FUNCTIONS OF NATURE 

These books will treat of the relation of facts to causes and 
effects— of heredity and the relations of organism to environment. 
8vo. 6|x8g in. 

Already publisht: 

THE BIRD : ITS FORM AND FUNCTION, by C. W. Beebe, 
Curator of Birds in the New York Zoological Park. $3.50 net; 
by mail, $3.80. 

Arranged for: 

THE INSECT: ITS FORM AND FUNCTION, by Vernon L. 
Kellogg, Professor in the Leland Stanford Junior University. 

THE FISH : ITS FORM AND FUNCTION, by H.M.Smith, of 
the U. S. Bureau of Fisheries. 

IV. WORKING WITH NATURE 

How to propagate, develop, care for and depict the plants and 
animals. The volumes in this group cover such a range of subjects 
that it is impracticable to make them of uniform size. 

Already publisht: 

NATURE AND HEALTH, by Edward Curtis, Professor Emeritus 
in the College of Physicians and Surgeons. 12mo. $1.25 net; 
by mail, $1.37. 

THE FRESHWATER AQUARIUM AND ITS INHABITANTS. 
A Guide for the Amateur Aquarist, by Otto Eggeling and 
Frederick Ehrenberg. Large 12mo. $2.00 net; by mail, $2.19. 



AMERICAN NATURE SERIES (Continued) ' 

IV. WORKING WITH NATURE (Continusd) 

THE LIFE OF A FOSSIL HUNTER, by Charles H. Sternberg. 
Large 12mo. $1.60 net; by mail, $1.72. 

SHELL-FISH INDUSTRIES, by James L. Kellogg, Professor 
in Williams College. 

THE CARE OF TREES IN LAWN, STREET AND PARK, by 
B. E. Fernow, Professor of Forestry, University of Toronto. 

Arranged for; 

PHOTOGRAPHING NATURE, by E. R. Sanborn, Photographer 
of the New York Zoological Park. 

CHEMISTRY OF DAILY LIFE, by Henry P. Talbot, Professor 
of Chemistry in the Massachusetts Institute of Technology. 

DOMESTIC ANIMALS, by William H. Brewer, Professor 
Emeritus in Yale University. 

INSECTS AND DISEASE, by Rennie W. Doane, Assistant Pro- 
fessor in the Leland Stanford Junior University. 

V. DIVERSIONS FROM NATURE 

This division will include a wide range of writings not rigidly 
systematic or formal, but written only by authorities of standing. 
Large 12mo. 5jx8£ in. 

Already publisht: 

INSECT STORIES, by Vernon L. Kellogg. $1.50 net; by mail, 
$1.62. 

FISH STORIES, by Charles F. Holder and David Starr Jordan. 
$1.75 net; by mail, $1.87. 

Arranged for; 
HORSE TALK, by William H. Brewer. 
BIRD NOTES, by C. W. Beebe. 

VI. THE PHILOSOPHY OF NATURE 

A Series of volumes by President Jordan, of Stanford Univer- 
sity, and Professors Brooks of Johns Hopkins, Lull of Yale, Thom- 
son of Aberdeen, Przibram of Austria, zur Strassen of Germany, 
and others. Edited by Professor Kellogg of Leland Stanford. 12mo. 
5|x7i in. 

Arranged for: 
THE STABILITY OF TRUTH, by David Starr Jordan. 



HENRY HOLT AND COMPANY, New York 
January, '10. 



AMERICAN INSECTS 

By VERNON L. KELLOGG 

PROFESSOR IN LELAND STANFORD, JR., UNIVERSITY 

WITH 812 figures and n colored plates; 647 pp. 
{American Nature Series, Group I); $5.00 net 
(postage 34 cents). Students' edition, $4.00. A 
comprehensive account of the natural history of the in- 
sects of America, written simply yet seriously, so as to 
be acceptable to the general reading public as well as to 
professional students of nature. All of the insect orders 
represented in our country are treated in this single 
volume, which, despite its comprehensiveness and its 
profusion of illustrations, is so compactly made as to be 
in no way unwieldy. The book may be used for con- 
tinuous reading by those wishing to inform themselves 
concerning the kinds and habits of American insects in 
general, or as a reference manual for authoritative in- 
formation on classification, specific remedies for certain 
pests, special discussions of structural, physiological, or 
ecological phases of insect biology, etc. 

41 Certain to be widely useful . . . readable and profusely illus- 
trated. It gives a great amount of information about the insects 
of this country, in such a manner that it is available to any intel- 
ligent person . . . other works are necessary for particular pur- 
poses ; but if I were asked to name a single work for a beginner, 
who at the same time meant business, I should not hesitate to 
recommend this new product of Stanford University."— T. D. A. 
Cocker ell in The Dial. 

" Nothing needed to make this a complete guide to the study of 
our American insects has been omitted." — M. A. Bigelow in the 
Independent. 

" Professor Kellogg's volume will be welcomed as one of the 
best general text-books on the subject covered." — C. L. Marlatt 
in Science. 

44 The work is scientifically conceived and carefully executed 
in every part ; but it is free from all unnecessary technicalities 
and so fresh in its spirit and so informal in its tone that one 
scarcely remembers in reading it the scientific attainments of its 
eminent author. It is a storehouse of biological information 
drawn from authoritative sources and vivified by contributions 
from the author's own rich experience as an observer and an in- 
vestigator. . . . The style is vivacious, flowing, correct, as pel- 
lucid as a mountain brook, and free from all those affectations of 
sprightliness or sentiment which seem likely to become conven- 
tional in the literature of nature study."— S. A. Forbes in School 
Science. 

44 An excellent work, and we can heartily recommend it to all 
who are interested in the classification and natural history of in- 
sects. It is written in an agreeable and attractive style and can 
bo referred to anywhere by the ordinary reader without fear of 
being disheartened by purely technical language . . . the greater 



part of the large volume is clear and simple and most interesting 
to every Nature Student. ... No one can take up the book and 
open it anywhere without becoming deeply interested in the sub- 
ject treated of, whatever it may be, provided, that is, that he has 
any love at all for living creatures, any interest in the myriad 
forms and modes of life of these wonderful beings that are 
everywhere about us." — Canadian Entomologist. 

" Sumptuous, delicate, exquisite, these are the words that easily 
leap to our lips in looking through the book. But I cannot too 
much emphasize the fact that in the volume we also have science 
made thoroughly readable."— i?. P. Powell in Unity. 

"Is probably the most valuable handbook of the subject for 
the technical student or amateur collector. 1 '— Kansas Farmer. 

" Ein ebenso reichhaltiges wie luxurios ausgestattetes Werk 
zur Einfuhrung in das Studium der Biologie der amerikanischen 
Insekten."— Edm. Reitter in Wiener Ent. Zeitung. 
"The book is of the first importance in its class."— Out West. 
" This work easily ranks as the most comprehensive volume 
treating of American insects yet produced. . . . The subject- 
matter is presented in an easy narrative style, though accuracy 
is not sacrificed for the sake of popularity. . . . The volume ex- 
hibits a thorough appreciation of and familiarity with recent in- 
vestigations. . . . This work brings together in one volume a 
vast amount of information and the author is to be congratulated 
upon having produced a very readable, comprehensive work, 
which should prove attractive and exceedingly helpful to the 
amateur as well as essential to every investigator."— E. P. Pelt 
in Psyche. 

"We have in this single volume a whole library of insect lore." 
-N. Y. Critic. 

" Es ist ein gewaltiges Unternehmen, das Verf . in diesem 
Werke zur Durchfiihrung gebracht hat und die vollendete Art 
und Weise dieser Durchfiihrung diirfte dem Buche in seinem 
Vaterlande einen vollen Erfolg sichern. Es will seinen Lesern 
eine Uebersicht fiber die gesammte Insektenwelt geben,aber nicht 
in dem oberflachlichen Feuilletonstil, den man in derartigen 
Werken haufig findet, sondern mit wirklichen wissenschaft- 
ficher Grfindlichkeit, und das ist dem Verfasser vorziiglich 
gelungen. "— Zeitschr. filr wissenschaftliche Insektenbiologie. 

" The work is probably the best that exists for anyone desiring 
an introductory work on North American insects compressed 
into a single volume."— David Sharp in Nature. 

" We are glad to see the interesting chapter on insects and dis- 
ease, as it places the subject on a higher plane with the general 
public, and is a matter of immense importance to humanity. 
Taking the work in its entirety it is a valuable contribution to 
the subject, and can't fail to be useful t-o the student beginner 
as well as to entomologists in general."— Entomological News. 

"To many readers, especially to those who, whilst studying 
specially one order, want a clear explanation of the general 
character and biology of the other orders, the book must be a 
precious boon, from which the fact that the illustrations are 
taken from American insects detracts nothing. Dr. Kellogg has 
long undoubtedly been in the first rank of American entomolo- 

fists, and this latest work can only add lustre to an already 
istinguished name."—/. W. Tutt in Entomologist's Record 
(London). 

HENRY HOLT AND COMPANY 

Publishers New York 



AMERICAN NATURE SERIES 

THE FRESHWATER AQUARIUM 
AND ITS INHABITANTS 

A Guide for the Amateur Aquarist. By Otto Eggeling and 
Frederick Ehrenberg. 

With 100 illustrations from photographs, large 12mo, 352 pp. 
$2.00 net; by mail, $2.19. 

A freshwater aquarium is far easier to maintain than either 
birds, plants, or domestic animals. It opens to easy observation 
a world of interesting plants and the locomotion, manner of feed- 
ing, of escaping from enemies of play, battle, and courtship of a 
multitude of creatures whose ways of life are entirely different 
from those of terrestrial organisms. 

This volume gives clear and complete instructions to the ama- 
teur. It describes and illustrates by some of the finest photographs 
ever taken from life, the great variety of plants, fishes, turtles, 
frogs, and insects that may be kept indoors in health and content- 
ment. It furnishes information concerning food, treatment in 
health and sickness, methods of capture and handling, and what 
aquatic creatures will or will not live in peace together. 

CONTENTS 

I. The Aquarium. 

II. Aquarium Plants. 

III. The Inhabitants of the Aquarium. 

IV. The Feeding of the Inmates of the Aquarium. 
V. Fish-hatching in the Aquarium. 

VI. Fish Maladies. 

VII. Implements for the Care and Keeping of the Aquarium. 

"The best guide to the aquarium."— The Independent. 

HENRY HOLT AND COMPANY 

Publishers New York 



By DAVID STARR JORDAN 

A GUIDE TO THE STUDY OF 
FISHES 

2 volumes, 934 illustrations. 1223 pp. $12.00 net, postage extra. 
32-pp. Prospectus on application. 

A comprehensive work, at once scientific and popular, by the lead- 
ing American ichthyologist. It discusses the structure, habits, evo- 
lution, and economic value of fishes. It treats of the characteristics 
of chief groups, emphasizing those which by reason of divergence 
from typical forms are of especial interest. Extinct fishes are dis- 
cussed along with their living relations. Nothing has been spared 
to make the work, in illustration and mechanical execution, worthy 
of a magnum opus. There is an abundance of pictures in half-tone 
and other forms of black-and-white illustration, and the frontispiece 
of each volume shows in colors some of the remarkable fish brought 
by the author from his Pacific explorations. There are also portraits 
of the world's leading ichthyologists. 

"The most comprehensive treatise on American Ichthyology."— The Dial. 

"The first large work on fishes to be independently undertaken by the writer, 
is of nearly twice the extent of Guenther's 'Introduction' or of the 'Cambridge 
Natural History ' and like them ' treats of the fish from all points of view.' . . . 
The author has given us the cream of his long experience and wide knowledge of 
American fishes and has made it full and attractive. There is no other accouut of 
the sort for American readers. "—Jacob Eeighard in Science. 

FISHES 

American Nature Series. 789 pp., 671 illustrations, 18 color plates*. 
$6.00 net, carriage 50 cents. 

This book includes virtually all the non-technical material contained 
in the author's larger work, "Guide to the Study of Fishes." The 
fishes used for food and those sought by anglers in America are treat- 
ed fully, and proportionate attention is paid to all the existing, as 
well as all extinct families of fishes. Notwithstanding the relative 
absence of technical material, it is expected that the book will be of 
value to students of ichthyology. Its chief aim, however, is to be of 
interest to nature-lovers and anglers and instructive to all who open 
its pages. 

" Of the highest value for the intelligent reader. An authoritative treatise and a 
readable essay."— Boston Transcript. 

"The author's wide knowledge of this group of animals, his comprehensive 
selection of interesting data, his terse, lucid, often humorous presentation, all com- 
bine to make this by far the most readable and interesting popular natural history 
of fishes."- The Dial. 

HENRY HOLT AND COMPANY 

PUBLISHERS NEW YORK 



LATEST VOLUMES IN 

THE AMERICAN NATURE SERIES 

(Prospectus of entire Series on request) 
THE CARE OF TREES IN LAWN, STREET, AND PARK 

By B. E. Fernow, of the University of Toronto. Illustrated. 
$2.00 net. 

Written for amateurs by a forester, this volume furnishes information 
such as the owner of trees or the " tree warden " may need. 

" Truly admirable . . . eminently practical. . . . His list of trees desirable 
for shade and ornament is a full and most valuable one, and the illustrations 
are enlightening."—^. Y. Tribune. 

HARDY PLANTS FOR COTTAGE GARDENS 

By Helen R. Albee, Author of " Mountain Playmates." 
Illustrated. i2mo. 

A personal and very readable record, illustrated by photographs, of the 
author's success in assembling within a limited area, the choice varieties of 
hardy shrubs, annuals, and perennials, so arranged as to give a succession of 
bloom of pure color in each bed. With a list giving manner of growth, 
height, time of blooming, exact color, special requirements of soil and 
moisture, " easy ways" taught by experience, and many et ceteras of vital 
importance. 

SHELL-FISH INDUSTRIES ^feX 

Illustrated by half-tones and original drawings. $1.75 net. 

Covers classification, propagation, and distribution. 

" Interests all classes, the biologist, the oyster grower, the trader and the 
eater of oysters. The science is accurate, and in some points new; it is 
made perfectly comprehensible and the whole book is very readable."— New 
York Sun. 

FISH STORIES: Alleged and Experienced, with a Little 
History, Natural and Unnatural 

By Charles F. Holder, Author of " The Log of a Sea 
Angler," etc., and David Starr Jordan, Author of " A Guide 
to the Study of Fishes," etc. With colored plates and many 
illustrations from photographs. $1.75 net. 

" A delightful miscellany, telling about fish of the strangest kind, with 
scientific description melting into accounts of personal adventure. Nearly 
everything that is entertaining in the fish world is touched upon and science 
and fishing are made very readable."— New York Sun. 

INSECT STORIES By Vernon L. Kellogg. 

Illustrated, $1.50 net. 

Strange, true stories, primarily for children, but certainly for those grown- 
ups who like to read discriminatingly to their children. 

" The author is among a few scientific writers of distinction who can 
interest the popular mind. No intelligent youth can fail to read it with 
delight and profit."— The Nation. 

HENRY HOLT AND COMPANY 

PUBLISHERS NEW YORK 



LIBRARY OF CONGRESS 

029 827 960 5 






